Results 1996



This is an annual report on the research activities in the field of optical communications and high-speed electron devices for 1996 at the Faculty of Engineering and Research Center for Quantum Effect Electronics, Tokyo Institute of Technology.

These activities are initiated by Professor Y. Suematsu (emeritus, the former president), and Professor S. Arai [Group A], mainly in the field of Semiconductor Photonic Devices including Low-dimensional Quantum-well Lasers, Photonic Switching Devices, and also in the fabrication of ultra-fine structures;

This report consists of a brief introduction of the research activities and a collection of the research papers published in 1996.

Publication List

Group members

  • Professor Emeritus
    • Yasuharu SUEMATSU
  • Professor
    • Shigehisa ARAI Ph.D.
  • Technical Assistant
    • Shigeo TAMURA B.S.
  • Secretaries
    • Sachiko ITAI B.A. -May
    • Kyoko KASUKAWA B.A. June-
  • Visiting Researcher
    • Gerd U. BACHER(a) Ph.D. -Nov.
  • Research Student
    • Yoon Ho PARK(1) M.S. -Aug.
  • Graduate Students
    (Doctor Course)
    • Ki Chul SHIN(2) M.S. -Mar.
    • Toshiyuki TAKIZAWA M.S.
    • Munehisa TAMURA M.S.
    • Takashi KOJIMA M.S. Apr.-
    • Mothi Madhan RAJ M.S. Oct. –
  • Graduate Students
    (Master Course)
    • Eijiro KIKUNO(3) B.S. -Mar.
    • Takashi KOJIMA B.S. -Mar.
    • Shinji KURIHASHI(4) B.S. -Mar.
    • Hirotsugu KASHOU(5) B.S. -Mar.
    • Madan RAJ B.S. -Sept.
    • Naoki SERIZAWA B.S.
    • Akira UCHINO B.S.
    • Xue Ying JIA B.S.
    • Toshikazu ANDO B.S. Apr.-
    • Hiroyuki NAKAYA B.S. Apr.-
    • Kazunori NUMATA B.S. Apr.-
    • Shi PENG B.S. Apr.-
    • Takehiro SHIMIZU B.S. Apr.-
  • Undergraduate Students
    • Toshikazu ANDO -Mar.
    • Makoto ITO(6) -Mar.
    • Masataka KONDO(7) -Mar.
    • Shi PENG -Mar.
    • Tetsuyuki NUMAGUCHI Apr.-
    • Nobuhiro NUNOYA Apr.-
    • Yasushi TAKEUCHI Apr.-
    • Suguru TANAKA Apr.-

Present Address

  • (1) the Maritime University, the Republic of Korea.
  • (2) LG Cable Co., the Republic of Korea.
  • (3) Sony Music Entertainments Co.
  • (4) Mitsubishi Corp.
  • (5) Toshiba Corp.
  • (6) Prof. Araki Lab., Tokyo Inst. Tech.
  • (7) Assoc. Prof. Munakata (Bs Lab., Tokyo Inst. Tech.)

On leave from

  • (a) Brzburg Univ., Germany.


Quantum-Film, Quantum-Wire, and Quantum-Box Lasers

Staffs: Y. Suematsu, S. Arai, M. Asada, M. Watanabe, S. Tamura
Visiting Researcher: G. Bacher
Research Student: Y. H. Park
Students: K. C. Shin, M. Tamura, M. Kumazawa, S. Kurihashi, T. Kojima, M. Madhan Raj, N. Serizawa, X. Y. Jia, H. Arima, T. Ando, S. Peng, M. Ito, M. Miura, H. Nakaya, K. Numata, S. Tanaka, N. Nunoya, T. Numaguchi, Y. Hayafune

GaInAsP/InP strained-quantum-film, -wire, and -box lasers have been studied both theoretically and experimentally.

Results obtained in this research are as follows:

(1) Temperature dependences of GaInAsP/InP compressively-strained single-quantum-well lasers with quantum-wire (Q-Wire) size active region were measured and compared with those of quantum-film lasers. Lower threshold current as well as higher differential quantum efficiency operation of Q-Wire laser than those of Q-Film laser at a temperature below 193K were obtained. Threshold current density of Q-Wire laser was 43A/cm2 which was almost a half that of Q-Film laser being 85A/cm2.

(2) From temperature dependence of emission wave length of Q-Wire lasers with different wire width, a clear blue shift (20meV for 15nm wire and 10meV for 20nm wire) was observed which was attributed to lateral quantum confinement.

(3) A room temperature CW operation of GaInAsP/InP multiple microcavity laser with etched mirrors was obtained. The threshold current density with broad contact (width W = 240mm, cavity length L = 60 mm) under pulsed operation was 180 A/cm2 (Ith = 20mA), and was 230 A/cm2 under CW condition.

(4) 1.3mm-wavelength Multiple Microcavity Laser with narrow groove (0.4mm) was fabricated using Cl2/H2 ECR dry-etching, which operated at 77K under CW optical pumping condition.

Semiconductor Photonic Devices

Staffs: S. Arai
Students: T. Takizawa, E. Kikuno, A. Uchino, T. Shimizu, M. Kondo, Y. Takeuchi

Semiconductor directional-coupler-type all-optical switching devices with tapered-shape structures were proposed and analyzed by numerical simulations. Moreover a GaInAs/InP multiple-quantum-well directional-coupler-type all-optical switch was fabricated and its low switching power operation was demonstrated.

Results obtained in this research are as follows:

(1) A semiconductor directional-coupler-type all-optical switch with tapered-shape structures, based on the nonlinear refractive index variation induced by photoexcited carriers, was proposed and its taper-shape dependence was investigated. By the numerical simulation, it is shown that an introduction of tapered-shape structures is effective for the improvement of the extinction ratio. It is also found that this device can drive the signal light of about 17dB higher power than the switching power.

(2) A GaInAs/InP multiple-quantum-well (MQW) directional-coupler-type all-optical switch utilizing the carrier-induced nonlinearity was fabricated and its low switching power operation was demonstrated at 1.55mm wavelength. Extinction ratios at each output port of 2.3dB and 2.6dB were obtained with low switching light power of 5.9mW at the input fiber end.

Processing for Nanometer Structures

Staffs: K. Furuya, S. Arai, M. Asada, Y. Miyamoto, M. Watanabe, M. Suhara, S. Tamura
Visiting Researcher: G. Bacher
Research Student: Y. H. Park
Students: T. Takizawa, H. Hongo, M. Tamura, T. Kojima, M. Kumazawa, S. Kurihashi, E. Kikuno, H. Tanaka, C. Nagao, H. Honji, X. Y. Jia, T. Ando, H. Hattori, H. Nakaya, A. Kokubo, S. Tanaka, N. Nunoya, Y. Hayafune, H. Nakamura

Study of nanometer structure fabrication technique is important for the realization of quantum effect devices such as quantum-wire or -box devices and ballistic electron devices based on wave characteristics of electrons.

Results obtained in this research are as follows:

(1) A high density InP triangular vertical pillar structure with a period of 40 nm was obtained by combining electron-beam lithography and anodization techniques.

(2) ECR-RIBE etching of GaInAsP/InP was investigated and characterized by PL intensity dependence on the pattern size.

(3) Conditional boundary between the step flow mode and the 2D-nucleation mode in GaInAs/InP OMVPE growth was obtained. Atomically flat terraces with monolayer steps were formed on both of InP and GaInAs surface.

(4) In EB lithography, the size distribution of dense multiple wire patterns (period: 50 nm) formed on EB-resist (ZEP-520) was measured and its deviation was reduced by proximity effect correction.

(5) Electrical properties of nanostructure is demonstrated. Contact current of 100-nm-pitch Cr/Au wire electrodes on GaInAs, and the current passing through the each wire are measured.

Financial Support

1. Grant-In-Aid from the Ministry of Education, Sports, Culture, Science and Technology, Japan.

Grant-In-Aid for Research Center for Ultra-high Speed Electronics
Grant-In-Aid for Research Center for Quantum Effect Electronics
Scientific Research (A, B, C)
Scientific Research on Priority Areas (Quantum Coherent Electronics)
Scientific Research on Priority Areas (Single Electron Devices)
Industry-University Joint Research Program (Mesoscopic Electronics)

2. Other Grant

Fellowship of the Japan Society for the Promotion of Science for Japanese Junior Scientists
Grant for "Research for the Future" Program from the Japan Society for the Promotion of Science (JSPS)
The Murata Science Foundation

3. Companies & Others

Anritsu Co.
Dupont Japan, Ltd.
Fujikura Co.
Fujitsu Laboratories, Ltd.
Furukawa Electric Industries Co., Ltd.
Kanagawa Academy of Science and Technology
Nippon Sanso Co.
Sumitomo Electric Industries, Ltd.
Tokyo Electron Tohoku Co., Ltd.

Nishiyama Laboratory
Quantum Nanoelectronics Research Core, Tokyo Institute of Technology

7F, S9-1, 2-12-1 O-okayama, Meguro-ku Tokyo 152-8552, Japan +81-3-5734-2555 ee.e titechnishiyama

Nishiyama lab. Student's room : South Bldg. 9 #701, #706, #707 | Measurement room : South Bldg. 9 #604, #502, #201 |
Clean room : South Bldg. 9 #202, B1F Exposure house | Research Laboratory of Ultra-High Speed Electronics