Yoshifumi Mori

Room-temperature continuous-wave operation of an AlGaInP double heterostructure laser grown by atmospheric pressure metalorganic chemical vapor deposition

Continuous‐wave (cw) operation at temperatures up to 23 °C of an Al0.26Ga0.26In0.48P/Ga0.52In0.48P/ Al0.26Ga0.26In0.48P double heterostructure (DH) laser has been achieved for the first time. The threshold current was 160 mA at 20 °C for a device with a 10‐μm‐wide and 250‐μm‐long ion‐implanted stripe geometry. The emission wavelength was 671 nm during cw operation at 10 °C. To reduce thermal resistance to a heat sink, a dually stacked structure made of a thin (∼0.3 μm) p‐AlGaInP layer and a p‐Al0.76Ga0.24As layer was used as a cladding layer. The DH wafer was grown by atmospheric pressure metalorganic chemical vapor deposition.

Optical properties of (AlAs)n(GaAs)n superlattices grown by metalorganic chemical vapor deposition

Optical properties were investigated on the superlattices with a unit lattice period of (AlAs)n(GaAs)n (n=1–24) which were grown by atmospheric‐pressure metalorganic chemical vapor deposition. Raman spectroscopy indicated that superlattice structure is realized for each n without collapsing into alloys. Photoluminescence measurement indicated that the ultrathin‐layer superlattice (with n larger than 2) has a direct energy gap, which is in good agreement with a tight‐binding calculation.

A New Etching Solution System, H 3 PO 4 ‐ H 2 O 2 ‐ H 2 O , for GaAs and Its Kinetics

A new solution system consisting of , , and was found useful for etching wafers. This solution system can be divided into four regions a–d, according to etching characteristics. The boundaries between the regions are given by a mole ratio of to of about 2.3 and a mole fraction of of about 0.9 at room temperature. Rate‐limiting processes are: a, adsorption of (, ); b, diffusion of (, ); c, dissolution of oxidized products (, ); and d, adsorption of (,). Solutions in region a have a reproducible etching rate of 0.01–0.1 μm/min, which is useful for MESFET processing. Crystallographic etching is also available with solutions in region c.

Electroluminescence in an Oxygen-Doped ZnSe p-n Junction Grown by Molecular Beam Epitaxy

Blue electroluminescence has been obtained from ZnSe p-n junctions. ZnSe films were grown on n-type GaAs(100) substrates by molecular beam epitaxy. The dopants used for n-and p-type ZnSe were Ga and O, respectively. The electron-beam-induced current strongly suggests the formation of a p-n junction. The built-in Potential of the p-n junction and carrier concentration of p-type ZnSe layer estimated from the capacitance-voltage relation were about 2.3 V and 1.2×1016cm-3, respectively. The electroluminescence spectra from the p-n junction were dominated by band-edge emissions of 466 nm at room temperature and 446 nm at 77 K.

Chemical trends in the activation energies of DX centers

The activation energies of DX centers in AlGaAs doped with six different impurities (S, Se, Te, Si, Ge, and Sn) are measured by deep level transient spectroscopy. Remarkable trends are established, in which the activation energies of DX centers with group IV impurities become shallower as the mass number of the impurity increases, while those with group VI impurities remain constant.

AlGaAs grown by metalorganic chemical vapor deposition for visible laser

Doping efficiency of selenium hydride (for Se donors) to GaAs in metalorganic chemical vapor deposition was shown to be high and near unity, whereas that of sulfur hydride (for S donors) was nearly two orders lower. The difference was even greater with the addition of aluminum to grow AlxGa1−xAs. Doping efficiency of diethyl zinc (for Zn acceptors) was shown to be three to four orders lower than of Se. A higher partial flow ratio of arsenic to column III elements was necessary to grow high‐quality layers of AlxGa1−xAs with larger x. Room‐temperature cw operation of AlxGa1−xAs/AlyGa1−yAs double heterostructure visible (760–780 nm) lasers grown by MOCVD has been achieved. The planar lasers, with an oxide‐insulated stripe structure 10 μm wide and 250 μm long showed a cw threshold current from 150 to 300 mA.

A proposal of a vacuum micro quantum interference transistor

A quantum interference transistor that can be fabricated by available technology and can operate at room temperature is proposed. This device uses the phase interference effect of a vacuum electron that is not influenced by thermal fluctuations, in contrast to an electron in solid‐state materials. The device consists of a field emitter, a collector, and segmented capacitors between the emitter and the collector. The capacitors control electron trajectories and the phase interference of the electron in vacuum by their electrical potential. This quantum interference effect is found not to be the same as the Aharonov–Bohm effect contrary to our expectations. We are convinced that the new transistor is capable of room‐temperature operation because the large kinetic energy of the electron in vacuum suppresses energy fluctuations caused by the field emission itself and by thermal fluctuations in the emitter material to about 50 meV. The switching time of the transistor is limited in order to average the number ...

MOCVD growth of AlGaInP at atmospheric pressure using triethylmetals and phosphine

Abstract (AlxGa1−x)0.5In0.5P quaternary alloy has been successfully grown by conventional atmospheric-pressure MOCVD using triethylaluminum, triethylgallium, triethylindium and phosphine as source materials. The relationship between photoluminescence (PL) line width and lattice mismatch ( δa a ) was examined. PL spectra at 4 K showed a line width narrower than 12 meV for layers with x less than 0.3 ( δa a ⩽ 1×10 −3 . Very narrow, down to 10 A thick (A10.5Ga0.50.5In0.5P/Ga0.5In0.50.5Ga0.5)0.5In0.5P quantum wells have been grown with no growth interruption at the heterojunction. 4 K PL spectra from 30 A thick GaInP double quantum wells separated by 5, 10 and 20 A thick A1GaInP barrier layers had a single peak, suggesting that no cluster on any significant size was formed in the A1GaInP alloy. An A1GaInP/GaInP double heterostructure laser operated continuously at room temperature with an emission wavelength from 670 to 680 nm.

Isoelectronic oxygen in II‐VI semiconductors

The properties of isoelectronic oxygen in II‐VI semiconductors were studied by photoluminescence measurements. It was found that oxygen in CdTe, CdS, and ZnS can act as an acceptor as well as in ZnSe, and that the acceptor levels of oxygen in CdTe, CdSe, and ZnS are shallower than those of typical acceptors such as Na. Charge transfer from the host lattice to the oxygen atom may play an important role in oxygen acting as an acceptor. Based on the charge‐transfer model, it can be qualitatively interpreted that there are two roles of oxygen in II‐VI compounds: acting as an acceptor or as a trap, and that they are classified by the ionicity of the compound. We also now understand better the chemical trend of the oxygen‐acceptor levels becoming more shallow compared to the typical acceptors.

Carbon incorporation in metalorganic chemical vapor deposition (Al,Ga)As films grown on (100), (311)A, and (311)B oriented GaAs substrates

The amount of carbon in GaAs and (Al,Ga)As films depends on the orientation of crystals grown by metalorganic chemical vapor deposition. We investigated the relation between the incorporation of carbon and the orientation of crystals using (100), (311)A, and (311)B substrates. The concentration of electrons on (311)B substrates of unintentionally doped films was higher than those of the films on (100) and (311)A substrates. The films grown on (311)B substrates did not show p‐type behavior even when they were grown with a fairly low V/III ratio. The relative intensity of the free‐to‐carbon acceptor luminescence of the films grown on (311)B substrates was smaller than that of films grown on the other substrates. This is consistent with the results of carbon contamination indicated by secondary ion mass spectra. Furthermore, a reduced peak in photoluminescence caused by defects was observed when (311)B substrates were used.