Hidetoshi Nishi

A New Functional, Resonant-Tunneling Hot Electron Transistor (RHET)

Abstract-A new functional, resonant-tunneling hot electron transistor (RHET) is demonstrated in which electrons are injected from emitter to base by resonant-tunneling through a quantum well, and are near-ballistically transferred to a collector. The main feature of this device is a peaked collector-current characteristic with respect to the base-emitter voltage. This enables us to build a frequency multiplier or an Exclusive-NOR gate using only one transistor.

Self‐aligned structure InGaAsP/InP DH lasers

Self‐aligned structure InGaAsP/InP DH lasers with emission wavelengths near 1.3 μm are studied. A cw threshold of about 100 mA is obtained in these lasers with cavity lengths of about 300 μm at a heat sink temperature of 25 °C. Light output increases linearly with current for outputs of 10 mW per facet and no kinks appear. Fundamental‐transverse and single‐longitudinal mode oscillation, and stable operation of fundamental‐transverse mode against injection current, are achieved. A cw operation up to 72 °C is obtained with a laser.

Tunneling Hot Electron Transistor Using GaAs/AlGaAs Heterojunctions

The first tunneling hot electron transistor (HET) using semiconductor heterojunctions has been achieved. This device uses GaAs/AlGaAs heterojunctions grown by molecular beam epitaxy and sophisticated process technology. Transfer efficiency for hot electrons through 100 nm thick n-GaAs was measured as 0.28.

Temperature characteristics of threshold current in InGaAsP/InP double‐heterostructure lasers

Temperature dependence of threshold current in InGaAsP/InP double‐heterostructure (DH) lasers was studied from the standpoint of the effect of carrier leakage from the quaternary active region into the InP confining layers. The carrier‐confinement coefficient, defined as the ratio of confined carriers to total injected carriers in the active region, was connected with other oscillation characteristics such as emission efficiency, carrier lifetime, and internal quantum efficiency in three different ways. These variations, as a function of ambient temperature, were measured and the temperature variation of the carrier‐confinement coefficient was evaluated and compared with that of threshold current. These results demonstrated that the carrier leakage was the dominant mechanism on temperature dependence of threshold current in InGaAsP/InP DH lasers. Moreover, we too discussed the other possibilities such as the effects of interfacial recombination at heterojunctions and laser parameters.

AlN capped annealing of Si implanted semi‐insulating GaAs

AlN capped annealing can be used successfully for thin n‐layer formation to minimize the thermal conversion effects. Si ions were implanted into Cr‐doped semi‐insulating GaAs substrates with 145 keV, to a dose of 2.40×1012 cm−2. Subsequently, the samples were annealed at 850 °C, 20 min with reactive sputtered AlN cap. The carrier profiles fit very well to the theoretical one. No thermal pits, cracks, and peeling‐off were observed even on 1.2‐μm‐thick AlN cap after up to 1000 °C annealing.

Improvement in GaAs MESFET performance due to piezoelectric effect

This paper describes the possibility of improving the performance of GaAs MESFETs by using piezoelectric effects. It is shown that piezoelectric charges, induced in the FET channel region due to the stressed dielectric overlayer, can be used to compensate for the deep tail of carrier distribution in the channel region. As a result, transconductance of short-channel GaAs FETs can be improved with a smaller shift in threshold voltage. The experimental results obtained for WSix- gate self-aligned MESFETs are qualitatively in good agreement with the theoretical values.

Migration of Mo atoms across Mo–Si interface induced by Ar+ ion bombardment

Backscattering analysis is used to investigate the effect of 150‐keV Ar ion bombardment on Mo thin films evaporated on silicon. Ar ion bombardment induces the migration of Mo atoms into the underlying substrate. These migration phenomena are caused mainly by an atomic recoil process, and depend on implanted ion dose and on film thickness. These phenomena are also affected by the peculiarity of the Mo–Si interface. The migration of Mo atoms occurs most noticeably at a thickness of 450±50 A, where about five Mo atoms for every incident Ar ion are introduced.

Uniform doping of channeled‐ion implantation

This paper describes an apparatus designed to obtain spatial uniformity of channeled‐ion implantation using a parallel‐scanning system. Descriptions of the special sample holder which can be tilted in two directions and a detecting scheme for channeling alignment are also included. This apparatus implanted channeled B ions along the [110] axis of silicon (Si). The variations of the implanted profiles and the breakdown voltages of the fabricated diodes in a wafer are compared with those obtained by random implantation and by channeled‐ion implantation using an angular‐scanning system. High doping uniformity comparable to that of random implantation is obtained reproducibly, proving that channeled‐ion implantation using a parallel‐scanning system can provide a controlled technique for device fabrication.

Depth distributions of defects and impurities in 100‐keV B+ ion implanted silicon

The depth distributions of boron atoms and of radiation‐induced defects are measured in the same set of silicon samples implanted with 100‐keV boron ions at room temperature to a dose of 1×1016/cm2, by utilizing the 11B(p,α)8 Be nuclear reaction and by channeling analysis with 1.5‐MeV He+ ions, respectively. Distributions of both boron atoms and the primary defects are asymmetric and significantly deviated from the Gaussian distribution. The width (FWHM) of the damage distribution is about 0.26 μ and is much larger than that of boron distribution which is 0.09 μ. The peak of the primary defect distribution is about 15% shallower than that of the boron distribution. The secondary defects have a Gaussian distribution, the peak depth of which almost coincides with that of boron distribution. The correlation between the electrical and the channeling measurements are also studied, and it is suggested that the secondary defects are strongly associated with boron atoms.

Ion implantation for high-speed III–V ICs

Abstract This paper describes the current technical state of ion implantation in III–V compounds for application to high speed ICs. Primary focus is on GaAs. Implantation into AlGaAs/GaAs heterostructures is also discussed. Effects of substrate quality, stress from capping materials and lateral diffusion of dopants on controlled doping required for IC fabrication are discussed. It is indicated that AIN is effective for minimizing the stress effect on doping. Rapid thermal annealing is suggested to be a promising technique for reducing lateral diffusion which induces a short channel effect. This technique will also be important for doping in heterostructures while minimizing the change in the interface properties.