K. Furuya

Etched mirror and groove-coupled GaInAsP/InP laser devices for integrated optics

Recent advances in wet and dry etching techniques for GaInAsP/InP laser structures allow the reproducible fabrication of planar and vertical walled facets and grooves. These elements provide efficient mirrors and interstage couplers that may provide the basis for a new generation of monolithic integrated optical devices. Initial experimental results on etched facet lasers and groove-coupled two-section lasers verify theoretical expectations.

Novel high‐speed transistor using electron‐wave diffraction

A new class of devices consisting of a heterojunction npn transistor with a wavelength modulator and a transversal potential grating in the base region is proposed. An electron injected at high energy into the base region is modulated in wavelength due to acceleration by a signal voltage and its transmission to the collector is controlled through diffraction caused by the grating. Diffraction characteristics are analyzed to reveal the possibility of high transconductances. Furthermore, a reduced transit time, which is due to the constant flow of high‐energy and collision‐free electrons and an extremely small capacitance between the modulation electrodes, provides significant potential for high‐speed logic applications.

Theoretical properties of electron wave diffraction due to a transversally periodic structure in semiconductors

Electron-wave diffraction caused by a grating structure is analyzed. In the grating, potential energy varies periodically in the direction perpendicular to the electron transport. Interference between models in the grating strongly affects diffraction efficiency. As a result, both high and low efficiency, about 90% and less than 1% respectively, can be obtained depending on the electron energy. Thus, the diffraction can be switched by changing the acceleration voltage of the electron. >

A novel deposit/spin waveguide interconnection (DSWI) for semiconductor integrated optics

We propose an efficient and simple optical interconnection between active semiconductor components by deposition and spin coating. Details of the waveguide design, the fabrication technique, and a promising material combination are given. Experimental results with an integrated laser-polyimide/SiO x ( x sim 2 ) waveguide combination demonstrate low-threshold (2.0 kA/cm2) laser operation and a low-loss waveguide interconnection (81 percent coupling efficiency) on a GaInAsP/InP chip.

OMVPE conditions for GaInAs/InP heterointerfaces and superlattices

Abstract This paper reports OMVPE growth conditions and evaluation of GaInAs/InP superlattices. In order to improve the heterointerface properties, transient responses of the mole flow rate caused by gas switching have been analyzed quantitatively. The required pressure drop just after the bubbler for stable supply of metalorganic sources was confirmed experimentally. Furthermore, it is pointed out that a compensating flow to maintain reactor atmosphere is also effective. GaInAs/InP superlattices grown by using these analytical results showed definite satellite peaks in the X-ray diffraction characteristics, definite steps in the absorption spectrum and a photoluminescence peak as narrow as 13 meV at 77 K.

Coherent Electron Devices

In conventional transistors, the transport of the electron is controlled using the incoherent interaction between the electron and fixed charges. This paper points out that the coherent interaction between the electron and fixed charges can provide more efficient control of the transport. To attain the coherent interaction, a systematic placement of impurity atoms in the crystal lattice is required. Atomic planes and atomic wires consisting of the impurity atoms will act as building elements for the coherent electron devices.

GaInAs/InP Hot Electron Transistors Grown by OMVPE

GaInAs/InP hot electron transistors were fabricated for the first time by using an organometallic vapor phase epitaxy (OMVPE) method. A base transport efficiency was measured as 0.52 at 77 K for the structure of a 160 nm thick Ga0.47In0.53As base and InP barrier layers. High energy peaks observed in current spectra suggested an appreciable hot electron transport. These show a promising potential of the OMVPE grown GaInAs/InP for its use in ballistic electron devices.

Electron wave diffraction by nanometer grating and its application for high‐speed transistors

This paper describes a new phenomenon about the diffraction of the ballistic electron by a transverse grating in the semiconductor. As a theoretical result, the diffraction efficiency changes almost between one and zero owing to a slight change in the average potential energy of the grating. For the grating of a 19‐nm pitch in GaInAs, we can change the diffraction efficiency between 0.88 and 0.001 by 0.1 V in the grating layer voltage. Applying this phenomenon to control of the electron transport, a new type of transistor is described.

OMVPE buried ultrafine periodic structures in GaInAs and InP

Abstract This paper describes fabrication methods for nanometer-pitch grating buried in the semiconductor for the future electron wave devices. Both wet chemical etching and selective growth are promising methods of grating formation on the surface of the semiconductor and also are damage-free processes. In the regrowth process to embed the grating, it is important to suppress the thermal deformation. Experimentally, InP corrugations 70nm-pitch grating were formed on InP surface in two ways — wet chemical etching and selective growth by OMVPE. InP gratings of 70nm pitch and 100nm depth were buried by OMVPE in GaInAs.

Negative differential conductance due to resonant states in GaInAs/InP hot-electron transistors

We have observed dips with negative values in the curve of the differential conductance of the base versus the base‐emitter voltage dIB/dVBE at 77 K in GaInAs/InP hot‐electron transistors grown by organometallic vapor phase epitaxy. The efficiency of the hot‐electron transmission across the 40‐nm‐thick base was more than 0.99. In comparison with a theoretical model considering that observed dips should have been caused by the resonant states in the base well, the phase relaxation time of the hot electron is estimated to be in the order of 0.1 ps or longer.