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Computer Solid state Physics Laboratory |
Takashi Iizuka
Professor |
Victor I. Ryzhii
Professor |
Irina I. Khmyrova
Assistant Professor |
Maxim V. Ryzhii
Research Associate |
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The research activity of the Computer Solid State Physics Laboratory is aimed at investigation of semiconductor quantum functional electronic and optoelectronic devices as a base for prospective computer hardware, intercomputer links and future communication systems. It is expected that by the end of the decade about 20 percent of the components in high performance computer systems will utilize quantum electron and photonic phenomena and this could progress further.
The efforts of the members of the laboratory are focused on
- Theory and computer modeling of quantum-well, -wire and -dot structures for quantum functional electron devices.
- Theory and computer modeling of photonic functional devices, in particular, photodetectors and high performance lasers.
- Development of novel mathematical models for simulation of quantum functional electronic and optoelectronic devices.
The results of the researchwere publishedin 24 refereed articles in the following journals:
- Physical Review B - 1,
- Journal of Applied Physics - 7,
- Applied Physics Letters - 2,
- IEEE Journal of Quantum Electronics - 1,
- Japanese Journal of Applied Physics - 1,
- Semiconductor Science and Technology - 2,
- Infrared Physics and Technology - 1.
The results also have been presented at the following conferences:
- Indium Phosphide and Related Materials (IPRM'01, Nara, Japan) - 2,
- Int. Workshop 'Quantum transport in Semiconductors (Maratea, Italy) - 1,
- Int. Workshop on Middle Infrared Coherent Sources (MICS-2001, St. Pe-tersburg, Russia) - 1,
- 10th Int. Conf. on Modulated Semiconductor Structures (MSS10, Linz,
Austria) - 1, 1
- 4th Int. Conf. on the Electronic Properties of Two-Dimensional Systems
(EP2DS-14, Prague, Czech Republic) - 1,
- Int. Conf. on Simulation of Semiconductor Processes and Devices (SISPAD
2001, Athens, Greece) - 1,
- 12th Int. Conf. on Nonequilibrium Carrier Dynamics in Semiconductors
(HCIS-12, Santa Fe, New Mexico, USA) - 1,
- 6th Int. Conf. on Intersubband Transitions in Quantum Well (Asilomar,
CA, USA) - 2,
- 8 Int. Workshop on Computational Electronics (IWCE-8, Urbana, Illinois,
USA) - 1,
- 28Int. SymposiumonCompoundSemiconductors(ISCS2001,Tokyo, Japan)
- 2, Photonics West (San Jose, USA) - 2,
- 2002 RCIQE Int. Seminar 'Quantum Nanostructures and Their Device Ap-
plications' (Sapporo, Japan) - 1.
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| [khmyrova-001:2001] | V. Ryzhii, I. Khmyrova, T. Ishibashi, S. V. Bandara, and S. D. Gunapala. High-Frequency Characteristics of Quantum Well Infrared Photodetectors with Blocking Barrier. Jpn. J. Appl.Phys., 40:3137-3142, 2001.
We have developed an analytical model for quantumwell infrared photodetectors(QWIPs) with a superlattice serving as the absorption region anda blocking barrier. The explicit analytical expression for the frequency-dependent responsivity is derived as a function of the QWIP structural parameters. Using this expression we calculate the 3 dB cut-o?? frequency and bandwidthresponse eAEciency.The band width of QWIP switha moderate number of QWs can exceed 100 GHz exhibiting fairly large responsivity. We show that a fast tunneling filling of the absorption region by the electrons injected from the emitter contact results in a significant modification of the high-frequencyproperties of the QWIP under consideration compared to the standard QWIPs, in particular, in the elimination of the low-frequency peak of the responsivity. |
| [khmyrova-002:2001] | N. Tsutsui, V. Ryzhii, I. Khmyrova, P.O.Vaccaro, H. Taniyama, and T.Aida. High-frequency performance of lateral p-n junction photodiodes. IEEE J. Quantum Electron., 37:830-836, 2001.
We developedan analytical device model for quantumwell lateral p-n junction photodiodes (LJPDs). Themodel takes into account the features of the carrier transport inLJPDsand their geometry, which ensure short transit times anda low capacitance. This model is used for calculating the LJPD's characteristics as functions of the signal frequency, bias voltage, and structural parameters and for the estimation of the LJPD ultimate performance. |
| [khmyrova-003:2001] | V. Ryzhii, N. Tsutsui, I. Khmyrova, T. Ikegami, P.O.Vaccaro, H. Taniyama, and T. Aida. Steady-state characteristics of lateral p-n junction vertical-cavity surface-emitting lasers. J. Appl. Phys., 90:2654-2559, 2001.
We developed an analytical device model for lateral p-n junction verticalcavity surface-emitting lasers (LJVCSELs) with a quantumwell active region. The model takes into account the features of the carrier injection, transport, and recombination in LJVCSELs as well as the features of the photon propagation in the cavity. This model is used for the calculation and analysis of the LJVCSEL steady-state characteristics. It is shown that the localization of the injected electrons primarily near the p-n junction and the reabsorption of lateral propagating photons signi??cantly e??ects the LJVCSELs performance, in particular, the LJVCSEL threshold current and power-current characteristics. The reincarnation of electrons and holes due to the reabsorption of lateral propagating photons can substantially decrease the threshold current. |
| [khmyrova-004:2001] | V. Ryzhii, I.Khmyrova, andM.Shur. Terahertz photomixing in quantum well structures using resonant excitation of plasma oscillations. J. Appl. Phys., 91:1875-1881, 2002.
We demonstrated that modulated infrared radiation can cause the resonant excitation of plasma oscillations in quantum well diode and transistor structures with high electron mobility. This effect provides a new mechanism for the generation of tunable terahertz radiation using photomixing of infrared signals. We developed a device model for a quantum well photomixer and calculated its high-frequency performance. It was shown that the proposed device can significantly surpass photomixers utilizing standard quantum well infrared photodetectors. |
| [m-ryzhii-001:2001] | M. Ryzhii and I. Khmyrova. Comment on 'Local responsivity in quantum well photodetectors' [J. Appl. Phys. 86, 7059 (1999)]. J. Appl. Phys., 89:6563-6564, 2001.
The response of multiple quantumwell(QW) infrared photodetectors(QW) to the photoexcitation of one QW selected from many identical QWs was recently modeled M.Ershov, J. Appl. Phys. 86, 7059 (1999). We point out here that the presented an alysis based on the use of drift-diffusion model for a system with a few electrons is incorrect. |
| [m-ryzhii-002:2001] | V. Ryzhii, M. Ryzhii, and H.C. Liu. Analysis of dual-band quantum well photodetectors. J. Appl. Phys., 91, 2002.
We present a simple but self-consistent analytical model for quantum well photodetectors for middle infrared and visible dual-band detection. The model takes into account photoexcitation of electrons from the quantum wells due to the intersubband absorption of middle infrared radiation and generation of electron-hole pairs caused by visible (or near infrared) radiation , electron injection from the emitter contact, and features of the electron and hole transport and capture in the photodetector active region. Using this model, we calculate the space charge and electric-field distributions and the photodetector responsivities in both spectral ranges. We demonstrate the formation of essentially nonuniform space charge and electric-field distributions in near the emitter contact and clarify the origin of steep responsivity-voltage characteristics. |
| [m-ryzhii-003:2001] | V. Ryzhii, M. Ryzhii, and H.C. Liu. Self-consistent model for quantum well photodetectors with thermionic injection in dark conditions. J. Appl. Phys., 92, 2002.
We present a self-consistent analytical model describing electron effects in quantum well infrared photodetectors(QWIPs)in dark conditions. The model takes into account thermionic emission of electrons from the quantum wells, thermionic electron injection from the emitter contact, and features of the electron transport and capture in the self-consistent electric field in the QWIP active region. Using an assumption that the rates of the electron escape from and capture into aQW are functions of the electric fields only in the barriers sandwiching this QW, we calculate the electric-field and charge distributions as well as dark current-voltage characteristics. We clarify the origin of steep dark current characteristics. It is confirmed that the effect of the emitter contact substantially weakens with increasing number of QWs in the QWIP structure. |
| [v-ryzhii-001:2001] | M. Ryzhii, V. Ryzhii, R. Suris, and C. Hamaguchi. Self-organization in multiple quantum well infrared photodetectors. Semicond. Sci. Technol., 16:202-208, 2001.
We investigate the spatio-temporal electric-field distributions in multiple quantum well infrared photodetectors (QWIPs) excited by infrared radiation using ensembleMonte Carlo particle modelling. It is shown that self-organized stable periodic electric-field structures canoccur in QWIPs excited by infrared radiation. These electric-field distributions have a period equal to twice the period of the QWIP structure. The periodic distributions are superimposed by relatively weak spatio-temporal oscillations. The transition between two stable periodic structures in response to step-like variation of the applied voltage is demonstrated. The periodicity of the electric-fueld structures is conserved after the cessation of illumination for a long time. This time is determined by relatively slow thermoexcitation processes. The occurrence of the electric-field distributions can pronouncedly affect the QWIP steady-state and noise characteristics. |
| [v-ryzhii-002:2001] | V. Ryzhii, I. Khmyrova, V. Pipa, V. Mitin, and M. Willander. Device model for quantum dot infrared photodetectors and their dark-current characteristics. Semicond. Sci. Technol., 16:331-338, 2001.
We propose a device model for quantum dot infrared photodetectors (QDIPs) with relatively large lateral spacing between QDs as occurs in QDIPs fabricated andexperimentally investigated recently. Thedevelopedmodel accounts for the self-consistent potential distribution and features of the electron capture and transport in realistic QDIPs in dark conditions. The model is used for the calculation of the dark current as a function of the structural parameters, applied voltage and temperature. It explains a rather sharp increase in the dark current with increasing applied voltage and its strong sensitivity to the density of QDs and the doping level of the active region. The calculated dependences are in good agreement with available experimental data. The obtained characteristics of QDIPs are compared to those of QWIPs with similar parameters. |
| [v-ryzhii-003:2001] | V. Ryzhii. Physicalmodelandanalysis ofquantumdot infrared photodetectors with blocking layer. J. Appl. Phys., 89:5117-5124, 2001.
A device model for quantum dot infrared photodetectors (QDIPs) with the blocking layer (BL) between quantum dots is presented. Explicit analytical formulas for the dark current and the responsivity in the QDIP of this type are obtained as functions of device parameters, including the doping level of the QDIP active region, andthe applied bias voltage. It is shownthat there are three voltage ranges in which the dark current and the responsivity of QDIPs reveal different behavior. The obtained results qualitatively explain some features of the QDIPs with BL observed experimentally. The characteristics of the QDIPs under consideration are compared with those of other detectors. |
| [v-ryzhii-004:2001] | V. Ryzhii. Negative di??erential photoconductivity inquantum-dot infrared photodetectors. Appl. Phys. Lett., 78:3346-3348, 2001.
We present a simple model for quantum-dot infrared photodetectors (QDIPs) describing nontrivial (decreasing) dependences of the photocurrent on theQD density and the applied voltage. It is shown that recent experiments demonstrating a negative di??erential photoconductivity in QDIPscan be interpreted in termsof this model. The e??ects under considerationcanbe attributed to the repulsive potential of charged quantum dots and heating of mobile electrons inffuencing the rate of the electron capture. Qualitative distinctions between the QDIP photocurrent-voltage and dark current-voltage characteristics are explained as well. |
| [v-ryzhii-005:2001] | V. Ryzhii and M. Ryzhii. Periodic electric-??eld and charge domains in multiple quantum well infrared photodetectors. Infrared Phys.Technol., 42:249-257, 2001.
We review the occurrence of periodic electric-??eld and charge domains in multiple quantum well infrared photodetectors under relatively strong illumination. The analysis of the formation of periodic domains and their features is based on both ensemble Monte Carlo particle simulations and original analytical models. |
| [v-ryzhii-006:2001] | V. Ryzhii, I. Khmyrova, V. Mitin, M. Stroscio, andM. Willander. On the detectivity of quantum-dot infrared photodetectors. Appl. Phys. Lett., 78:3523-3525, 2001.
We report on the analysis of thermally-limited operation of quantum-dot infrared photodetectors (QDIPs). A device model is developed and used to calculate the QDIP detectivity as a function of the structural parameters, temperature, and applied voltage, as well as to determine the conditions for the detectivity maximum. The QDIP detectivity is compared with that of quantum-well infrared photodetectors (QWIPs). This work clarifies why the existing QDIPs are still inferior to QWIPs and shows that a significant improvement in the QDIP performance can be accomplished by the utilization of dense QD arrays with small QDs. |
| [v-ryzhii-007:2001] | W. Xu, I. Khmyrova, and V. Ryzhii. Terahertz-photon-modified magneto transport in a semiconductor in Voigtgeometry. Phys. Rev. B, 64:085209, 2001.
We present a theoretical study of transport and optical properties of a semiconductor-basedelectron gassubjected simultaneously to quantizing magnetic fields and intense terahertz (THz) laser fields in Voigt geometry. It is found that the presence of the THz radiation can result in an enhanced magnetophonon resonance effect and a resonant-absorption peak can be observed at about f 1THz for GaAs in high magnetic fields. The results are pertinent to experiments where THz free-electron lasers are employed as intense radiation sources. |
| [v-ryzhii-008:2001] | V. Ryzhii and H.C. Liu. Photonic breakdown in up-conversion imaging devices based on the integration of quantum-well infrared photodetector and light-emitting diode. J. Appl. Phys., 2002.
We analyze the effect of photon recycling on up-conversion in a heterostructure device including a quantum well infrared photodetector (QWIP) integrated with a light emitting diode (LED). Such a QWIP-LEDdevice converts middle infrared radiation into near infrared (NIR) or visible radiation (VIR) utilizing intersubband transitions in the QWIP and interband transitions in the LED. We show that the reabsorption of NIR/VIR photons in the QWIP can substantially a??ect the up-conversion of both uniform illuminations and infrared images. As demonstrated, this e??ect can cause a photonic breakdown associated with apositive feedbackbetween the emission ofNIR/VIR photons from the LED and the resulting photocurrent in the QWIP. |
| Referred Proceeding Papers |
| [khmyrova-005:2001] | V. Ryzhii, I. Khmyrova, and M. Shur. Resonant plasma mechanism of terahertz photomixing in quantum well structures. In 6th Int. Conf. on Intersubband Transitions in Quantum Wells, page T3.3, Asilomar, CA, USA, Sept. 2001.
The purpose of this paper is to show that inquantum well structure with high electron mobility modulated infrared radiation can excite plasma oscillations with the THz frequencies. |
| [khmyrova-006:2001] | V. Ryzhii, H. Sagawa, and I. Khmyrova. Low temperature effects in quantum dot infrared photodetectors. In 6th Int. Conf. on Intersubband Transitions in Quantum Wells, page M4.6, Asilomar, CA, USA, Sept. 2001.
In this communication we consider the QDIP operation invoking a physical model generalized in comparisonto previously used one focusing on low temperatures when the electron heating and tunneling are essential and explain such features of the QDIP behavior. |
| [khmyrova-007:2001] | I. Khmyrova, N. Tsutsui, V. Ryzhii, P.O.Vaccaro, K. Kubota, T. Aida, and T.Ikegami. Physical model for lateral p-n junction vertical-cavity surface-emitting lasers. In 28 Int. Symposium on Compound Semiconductors (ISCS2001), page 89, Tokyo, Japan, Oct. 2001.
In this work, we develop a physical device model for VCSELs with a lateral p-n junction in the active layer similar to those fabricated and measured recently. The model takes into account the features of the carrier injection, transport, and recombination as well as the features of the photon propagation in the cavity. We use this model for the analysis of the VCSEL steady-state characteristics. |
| [m-ryzhii-004:2001] | R. Suris, V. Ryzhii, and M. Ryzhii. Is QWIP a simple device Current induced instabilities and inhomogeneous structures in QWIPs. In Int. Workshop on Middle Infrared Coherent Sources (MICS-2001), St Petersburg, Russia, Jun. 2001.
The occurence of nontrivial e??ects in quantum well infrared photodetectors strongly affecting their operation is predicted and discussed |
| [m-ryzhii-005:2001] | M. Ryzhii and V. Ryzhii. Ensemble Monte Carlo particle modeling on InGaAs/InP uni-traveling-carrier photodiodes. In Int. Conf. on Simulation of Semiconductor Processes and Devices (SISPAD 2001), Athens, Greece, Sept . 2001.
In this communication, we report the study of electron and hole non equilibrium phenomena and transient response of uni-traveling-carrierphotodiodes. For this purpose we use an ensemble Monte Carlo (MC) particle technique similar to that used previously for the studies of the transient processes in bipolar heterostructure transistors and quantum well infrared photodetectors and adjusted to the structural features of UTC photodiodes. |
| [v-ryzhii-009:2001] | N Tsutsui, I. Khmyrova, V. Ryzhii, P.O. Vaccaro, H.Taniyama, and T. Aida. Theoretical analysis of transient processes in lateral p-n junction photodiodes. In Indium Phosphide and Related Materials (IPRM'01), pages 158-161, Nara, Japan, May. 2001.
We present an analytical device model for quantumwell lateral p-n junction photodiodes (LJPDs) which takes into account the features of the carrier transport in LJPDs and their geometry. These features ensure short transit times and a low capacitance. |
| [v-ryzhii-010:2001] | V. Ryzhii, I. Khmyrova, V. Pipa, M. Ryzhii, V. Mitin, and M. Willander. Physical model and characteristics of quantum dot infrared photodetectors. In Indium Phosphide and Related Materials (IPRM'01), pages 382{385, Nara, Japan, May. 2001.
We develop a physical model for quantum dot infrared photodetectors (QDIPs). The dark current and photocurrent in QDIPs as functions of the QDIP structural parameters and the applied voltage are calculated. |
| [v-ryzhii-011:2001] | V. RyzhiiandV. Mitin. Electron transport and infraredphotoconductivity in quantum dot structures. In Int. Workshop 'Quantum transport in Semiconductors', Maratea, Italy, Jun. 2001.
We consider a physical model for monopolar quantum dot (QD) structures. The obtained results clarify some interesting features of infrared photodetectors based on the QD structures observed experimentally, in particular, a rather steep (exponential) rise of the dark current and photocurrent with the applied voltage and the occurrence of the negative differential photo conductivity. |
| [v-ryzhii-012:2001] | V. Ryzhii, I. Khmyrova, M. Willander, and V. Mitin. Theoretical analysis of electron transport in quantum dot structures. In 10th Int. Conf. on Modulated Semiconductor Structures (MSS10), page ThP14, Linz, Austria, Jul. 2002.
We presented an analytical model for electron transportphenomenain diode structures with multiple quantum dot arrays. The model takes into account the electron capture intoand emission fromquantumdots aswell as the electron injection from the emitter contact. Using this model we calculated dark current-voltage and photocurrent voltage characteristics and explained their exponential behaviour. The obtained results can be used for the in-depth understanding of the operation of quantum-dot infrared photodetectors and their optimization. |
| [v-ryzhii-013:2001] | V. Ryzhii. Negative di??erential infrared photoconductivity in quantum dot structures. In 14th Int. Conf. on the Electronic Properties of Two-Dimensional Systems (EP2DS-14), Prague, Chech Republic, Aug. 2001.
Using a simple model for monopolar quantum-dot structures which takes into account the heating of mobile (unbound) electrons, we calculated the current-voltage characteristics of these structures under infrared illumination and revealed the origin of the e??ect of negative differential infrared photoconductivity observed in recent experiments. |
| [v-ryzhii-014:2001] | V. Ryzhii, V. Mitin, and M. Stroscio. Hot electrons and negative di??erential photoconductivity in quantum dot infrared photodetectors. In 12th Int. Conf. on Nonequilibrium Carrier Dynamics in Semiconductors (HCIS-12), Santa Fe, New Mexico, USA, Aug. 2001.
Electron heating by the electric field in quantum dot photodetectors and its effect on their characteristics is discussed. The origing of the negative differential photoconductivity observed previously experimentally is clarified |
| [v-ryzhii-015:2001] | V. Ryzhii and V. Mitin. Quantum dot infrared photodetectors: Physical model and problems of computer simulation. In 8 Int. Workshop on Computational Electronics (IWCE-8), Urbana, Illinois, USA, Oct. 2001.
The proposed model explains the following experimental facts: (1) exponential character of dark current-voltage and photocurrent-voltage char acteristics; (2) relative steepness of dark current-voltage characteristics; (3) negative di??erential photoconductivity at low temperatures. |
| [v-ryzhii-016:2001] | V. Ryzhii, H. Sagawa, V. Mitin, and M. Stroscio. Tunneling and hot electron transport in monopolar quantum dot structures. In 28 Int. Symposium on Compound Semiconductors (ISCS2001), page 161, Oct. 2001.
In this communication we generalize the physical model for QD structures by the inclusion of the electron tunneling and heating e??ects and study the inffuence of these e??ects on the current-voltage characteristics of QD structures both |
| [v-ryzhii-017:2001] | V. Ryzhii, I. Khmyrova, V. Mitin, M. Willander, and M.A. Stroscio. Physics of quantum dot infrared photodetectors and their ultimate performance. In Photonics West, pages 4656-07, San Jose, USA, Jan. 2002.
Recent studies of physical phenomena in quantum dot infrared photodetectors (QDIPs) are reviewed. We show that the improvement of QDIPs, and creation of novel QDIP-based devices still requires an in-depth understanding of underlying physical effects. |
| [v-ryzhii-018:2001] | V. Ryzhii, I. Khmyrova, N. Tsutsui, P.O. Vaccaro, H. Taniyama, T. Aida, and T. Ikegami. Lateral p-n junction VCSELs: Device physics and characteristics. In Photonics West, pages 4646-19, San Jose, USA, Jan. 2002.
We developed a physical and matematical model for a novel promising and interesting semiconductor device - lateral p-n junction VCSEL. The developed model explains a reduced threshold current and other features of the device characteristics. |
| [v-ryzhii-019:2001] | V. Ryzhii. Physics andmodeling of quantumwell and quantum dot devices. In 2002 RCIQE Int. Seminar 'Quantum Nanostructures and Their Device Applications', pages 54{59, Sapporo, Japan, Feb. 2002.
We review recent studies of physical phenomena in quantum well infrared photodetectors (QWIPs), and some other QWandQD infrared devices and discuss their features. |
| [v-ryzhii-020:2001] | V. Ryzhii. Research on computer modeling for simulation and optimization of lateral-junction devices, ATR Adaptive Communication Research Laboratories, 2002. |
| [khmyrova-008:2001] | Irina Khmyrova, 2002.
Senior Member, The Institute of Electrical and Electronics Engineers, USA
(1994.03 - to present) |
| [khmyrova-009:2001] | Irina Khmyrova, 2002.
Member, American Physical Society (1995.07 - lifelong membership)
[khmyrova-010:2001] Irina Khmyrova, 2002. Associate Member, The Third World Organization for Women in Science,
Trieste, Italy (1992.02 - to present) |
| [m-ryzhii-006:2001] | Maxim Ryzhii, 2002.
Senior Member, The Institute of Electrical and Electronics Engineers, USA
(1996.01 - to present) |
| [m-ryzhii-007:2001] | Maxim Ryzhii, 2002.
Member, American Physical Society, USA (1995.07 - lifelongmembership) |
| [v-ryzhii-021:2001] | Victor Ryzhii, 2002.
CorrespondingMember, RussianAcademy of Sciences (Brunch of Informatics,
Computer Engineering and Automation)(1987.12 - lifelong membership) |
| [v-ryzhii-022:2001] | Victor Ryzhii, 2002.
Senior Member, The Institute of Electrical and Electronics Engineers, USA
(1994.03 - to present) |
| [v-ryzhii-023:2001] | Victor Ryzhii, 2002.
Member, American Physical Society, USA (1995.07 - lifelong membership) |
| [v-ryzhii-024:2001] | Victor Ryzhii, 2002.
Member (1993.11 - to present) |
| [v-ryzhii-025:2001] | Victor Ryzhii, 2002.
Member, The Institute of Electronics, Information andCommunication Engi-
neers of Japan (1993.07 - to present) |
| [v-ryzhii-026:2001] | Victor Ryzhii, 2002.
Member of Editorial Board, Journal `Microelectronics' Russian Academy of
Sciences (1990.01 - to present) |
| [v-ryzhii-027:2001] | Victor Ryzhii, 2002.
Adjunct ProfessorWayne StateUniversity, Detroit, USA(1995.08- topresent) |
| [v-ryzhii-028:2001] | Naoaki Tsutsui. Master Thesis: Modeling of photon recycling effect in light emitting diodes and vertical cavity surface emitting lasers, University of Aizu, 2002.
Thesis Advisor: Victor Ryzhii. |
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Annual Review 2001