S. Mukai

Bio: S. Mukai is an academic researcher from California Institute of Technology. The author has contributed to research in topics: Semiconductor laser theory & Laser. The author has an hindex of 5, co-authored 6 publications receiving 50 citations.

Paired, separately controlled, and coupled or uncoupled stripe geometry semiconductor lasers

Abstract: An integrated laser structure for paired stripe semiconductor lasers is provided with separate current control of each stripe laser. With optical coupling between the lasers, one of the lasers is operated below threshold and serves the longitudinal mode selection and tunability of the other laser, thereby to obtain a single longitudinal mode operation. Without coupling, the paired-laser structure operates as a source of two independent wavelengths.

Vertical field‐effect transistors in III‐V semiconductors

Abstract: Vertical metal‐semiconductor field‐effect transistors in GaAs/GaAlAs and vertical metal‐oxide‐semiconductor field‐effect transistors (MOSFET’s) in InP/GaInPAs materials have been fabricated. These structures make possible short channel devices with gate lengths defined by epitaxy rather than by submicron photolithography processes. Devices with transconductances as high as 280 mS/mm in GaAs and 60 mS/mm (with 100‐nm gate oxide) for the InP/GaInPAs MOSFET’s were observed.

Coupled parallel waveguide semiconductor laser

Abstract: The operation of a new type of tunable laser, where the two separately controlled individual lasers are placed vertically in parallel, has been demonstrated One of the cavities (‘‘control’’ cavity) is operated below threshold and assists the longitudinal mode selection and tuning of the other laser With a minor modification, the same device can operate as an independent two‐wavelength laser source

Vertical FET's in GaAs

Abstract: Vertical FET's in GaAlAs material systems have been fabricated. The present structure makes possible extremely short (less than 1000-A) channel devices which are beyond the reach of optical lithographic processes. Devices with transconductance g m as high as 280 mS/mm have been obtained.

Mutual phase locking of a coupled laser diode‐Gunn diode pair

Abstract: Mutual phase locking has been achieved through series connection of a semiconductor laser and a Gunn diode oscillator. Experimental results obtained demonstrate a mutual interaction between the two oscillators which results in a short term Gunn diode oscillator stability and improved spectral purity of its output. We also observe a narrowing of laser pulses and an improvement in regularity.

Crystal orientation dependence of silicon doping in molecular beam epitaxial AlGaAs/GaAs heterostructures

Abstract: Results on crystal orientation dependence of n‐ and p‐type Si doping in molecular beam epitaxial GaAs are presented. High electron and hole mobilities in AlGaAs/GaAs heterostructures on high index planes are demonstrated for the first time. The doping results should prove useful for various transistor structures and complementary circuits. Also, due to the differences in the band structure for different orientations, quantum well heterostructures are likely to exhibit many interesting phenomena which are strongly orientation dependent.

Patterned electrode vertical field effect transistor fabricated using block copolymer nanotemplates

Abstract: We report the design and implementation of a vertical organic field effect transistor which is compatible with standard device fabrication technology and is well described by a self consistent device model. The active semiconductor is a film of C60 molecules, and the device operation is based on the architecture of the nanopatterned source electrode. The relatively high resolution fabrication process and maintaining the low-cost and simplicity associated with organic electronics, necessitates unconventional fabrication techniques such as soft lithography. Block copolymer self-assembled nanotemplates enable the production of conductive, gridlike metal electrode. The devices reported here exhibit On/Off ratio of 104.

Semiconductor heterojunction topics: Introduction and overview

Abstract: Semiconductor heterojunctions with ideal lattice matching, well-controlled in fabrication, yield devices that cannot be achieved in any other way. These devices include modulated-doped high-speed field-effect transistors, ultra-high-gain and high-speed bipolar transistors, efficient injection lasers and light-emitting diodes and sensitive photo-detecting structures. Atomic reconstructions take place at heterojunction interfaces and are process-fabrication-dependent and not adequately understood. The barrier discontinuities observed are therefore scattered in value and also somewhat dependent on the determination method. Many papers in this Special Issue contain review aspects of these matters. Others, however, are specific contributions on very particular heterojunction topics. Not all aspects of heterojunctions are dealt with by the papers that follow, and the present article is intended for newcomers to the field as a brief commentary on topics that are not adequately represented.

Double diamond mesa vertical field effect transistor

Abstract: A double diamond mesa vertical field effect transistor includes a diamond layer, a first diamond mesa on a diamond layer, and a second diamond mesa on the first diamond mesa, opposite the diamond layer. A source contact is formed on the second diamond mesa, opposite the first diamond mesa, and a gate is formed on the first diamond mesa opposite the diamond layer. The drain contact may be formed on the diamond layer adjacent the first diamond mesa, or the diamond layer itself may be formed on a nondiamond substrate and a drain contact may be provided on the nondiamond substrate. An integrated array of field effect transistors may be formed, including a plurality of second mesas on the first mesa, with a plurality of gates formed on the first mesa between the second mesas and a source formed on each second mesa, opposite the first mesa. The second mesas may also extend over the multiple gate contacts on the first mesa to form a common source region with a common source contact. The double mesa vertical field transistors may be formed by selective deposition of the first and second mesas on a diamond layer or by etching the first and second mesas in the diamond layer. Selectively epitaxial lateral overgrowth of the second diamond mesas on the first diamond mesa may be used to form a common source contact over multiple gates.

Passive and active mode locking of a semiconductor laser without an external cavity

Abstract: This letter describes the first attempt to passively and actively mode lock a discrete semiconductor laser, i.e., one not coupled to an external cavity. Beat notes of the longitudinal modes of a 1.97-mm-long GaAlAs laser have been observed at 17.7 GHz. The spectral width of the beat note was approximately 100 kHz. Stable passive mode locking has been observed under appropriate operating conditions. Active mode locking by an externally injected microwave signal was also achieved.