Makoto Morioka

A New Two-Dimensional Electron Gas Field-Effect Transistor Fabricated on Undoped AlGaAs–GaAs Heterostructure

A new two-dimensional electron gas (2DEG) field-effect transistor (FET) which operates in an MOS transistor-like mode is fabricated on undoped AlGaAs–GaAs heterostructures grown by both molecular beam epitaxy and organometallic vapour phase epitaxy. This device with very simple structure is expected to have performance comparable to those of selectively doped heterostructure FETs and can easily be integrated.

Low temperature MBE growth of high quality AlGaAs

Abstract High quality AlGaAs MBE layers have been successfully grown at very low temperatures (

Near-infrared high-power LED's with Ga 1-x Al x As epitaxially grown junctions

This paper reports on a study of several techniques of fabricating an efficient Ga 1-x Al x As IRED with high power. Smooth epitaxial layers are grown on a substrate containing a thick Ga 1-x Al x As epitaxial layer which is used to form a hemispherical emitting surface. This is achieved by using a melting-back technique without up-heating. An effect of the AlAs molefraction ratio between n- and p-type regions was clearly found by measurement of a large number of diode chips, and the best performances were obtained on the junctions with the ratio X_{n}/X_{p} simeq 1.5 . Ohmic contacts to the p and n regions were applied on the same surface of the wafer using only one metallic source for the vacuum deposition. A cerium-oxide film serves as an antireflection coating when deposited on the hemispherical surface and increases the optical output power by more than 30 percent. External quantum efficiencies of 28 percent (current density: 400 A/ cm2) and optical output power of 96 mW (drive current: 300 mA, current density: 1500 A/cm2) have been observed from diodes emitting at 8300 A under dc operation at room temperature.

Determination of band-gap discontinuity in AlGaAs/GaAs system by quantum oscillations of photoluminescence intensity

Abstract An anomalous excitation intensity dependence of photoluminescence (PL) in high-quality Al0.3Ga0.7As/GaAs quantum wells was observed at low temperatures. The PL intensity IPL was seen to increase as IPL ∝ IEXm with increasing excitation intensity IEX and the power m varied periodically between 1 and 2, depending on the well width. This phenomenon can be understood in terms of the carrier trapping efficiency under resonant and off-resonant conditions. From the theoretical analysis of the effect, the conduction band off-set can be estimated to be 59–70%, considerably smaller than the value of Dingle et al.