Tokuzo Sukegawa

Gravity effect on dissolution and growth of silicon in the In-Si system

Abstract Epitaxial growth of silicon from an indium solution and dissolution of silicon in the Earths gravitational field are considered. We examined the epitaxial growth and dissolution using a horizontal substrate-solution-substrate “sandwich” system under near isothermal conditions. Remarkable differences between substrates above and below a solution were observed. These phenomena are discussed in terms of the effect of gravity on mass transport in the growth solution. We propose a new growth technique, called the “yo-yo solute feeding method”, using cyclic temperature modulation.

The solute-feeding Czochralski method for homogeneous GaInSb bulk alloy pulling

Abstract A technique of pulling a homogeneous alloy from GaSb-InSb pseudo-binary solution under GaSb solute-feeding conditions has been developed. A two-chamber crucible, in which a small hole controlled solute supply from the source chamber to the growth chamber, realized two conflicting conditions required for stable CZ-mode growth (non-equilibrium) and for keeping a constant composition (near-equilibrium). With the use of a GaSb seed crystal , a GaInSb bulk alloy with uniform InSb content of 3 mol% was pulled at a constant temperature of 691°C. Subsequently, using this grown alloy as the second seed, an alloy of 15 mm diameter and 20 mm lenght with InSb content of 5 mol% could be pulled at 672°C.

Highly efficient pGaSb‐nGa1−xAlxSb photodiodes

Highly efficient pGaSb‐nGa1−xAlxSb photodiodes were fabricated by liquid‐phase‐epitaxial growth of an undoped p‐type GaSb layer, followed by that of an n‐type Ga1−xAlxSb layer with a composition at x=0.7 on a p‐type (100) GaSb substrate. Spectral photocurrent response of the diodes measured at various bias voltages and room temperature was fairly flat between 1.0 and 1.7 μm. The external quantum efficiency of the photoresponse was 38% at zero bias and 54% at 1 V reverse bias in the vicinity of 1.2 μm.

Gravity effect on solute transport in dissolution and growth of silicon

Dissolution of silicon in an indium solution in the Earths gravitational field is considered. We examined the dissolution using a substrate-solution-substrate “sandwich” system under near isothermal conditions. A remarkable difference was observed between substrates above and below the solution. This phenomenon is discussed in terms of solutal convection in the solution. A numerical description of this convection and its effect on the dissolution process is given. Comparison with experimental data shows that the observed phenomenon can be explained on the basis of the solutal convection model.

Bipolar-mode static induction transistor: experiment and two-dimensional analysis

A bipolar-mode static induction transistor (BSIT) with a simple planar structure as an experimental device has been fabricated. Two-dimensional numerical simulation has been used to investigate the operational principle for the BSIT with the pentode-like shape revealed by the output characteristics. Using the simulation, the variation of the potential barrier as a function of the bias voltages has been explained. The results show that the potential barrier is varied uniquely according to the physical condition of the conduction channel determined by the external bias voltages. This variation can be explained easily with the DC circuit models originating from the physical conditions of the conduction channel. The analysis shows that the current in the BSIT is controlled in a complex manner by the voltages. >

Control of GaInSb alloy composition grown from ternary solution

Abstract The solute-feeding Czochralski method developed to grow a homogeneous bulk alloy from a pseudo-binary solution has been expanded to a ternary solution system. To keep the alloy composition constant, two parameters of growth temperature and source composition were fixed. By establishing a special growth condition, the alloy composition was prevented from thermal disturbance. The growth of a homogeneous Ga 0.4 In 0.6 Sb alloy is demonstrated.

Preparation of lithium niobate films by metalorganic chemical vapor deposition with a lithium alkoxide source

Li(OBut) was examined as a Li source in low pressure metalorganic chemical vapor deposition (LP-MOCVD). Vapor species of Li component and Nb component (from a Nb (OEt)5 source) carried with argon gas were blown on a SiO2Si substrate heated at 450–630°C. The deposited films were confirmed to be crystalline LiNbO3 by X-ray diffraction.

Pulling Technique of a Homogeneous GaInSb Alloy under Solute-Feeding Conditions

Stable growth under solute-feeding conditions was realized using a two-chamber (growth and source) crucible, in which a small hole connecting the two chambers was used to control the solute supply from the source region. A piston mechanism pushed up the solute source in the source chamber to keep the volume in the growth region constant during growth. With use of a GaSb seed crystal, a GaInSb bulk alloy of 13 mm diameter and 12 mm length with uniform InSb content of 3 mol% was successfully pulled from GaSb-InSb pseudo-binary solution at a constant temperature of 677°C.

Low temperature phase diagram of In-Ga-P ternary system

Abstract The In—Ga—P ternary phase diagram in the low temperature region, 600–800°C, in the In-rich corner has been experimentally obtained and calculated based on the quasi-regular model with the assumption of a non-ideal solid. The liquidus lines were determined at 600, 650, 700, 750 and 800°C by weight loss method. The solidus compositions were measured on the epitaxial layers grown by the temperature difference method. Fairly good agreement between the data and calculated results was obtained.

Reproducible Preparation of Homogeneous In1−xGaxP Mixed Crystals

A solution‐growth method was developed to obtain highly homogeneous In1−xGaxP mixed crystals. In this method, a GaP crystal was the source material which was placed in the high‐temperature portion of the In solution. An In1−xGaxP mixed crystal of a controlled composition crystallized in the low‐temperature portion of the solution. The temperature of the solution and the vapor pressure of phosphorous were maintained constant in order to obtain mixed crystals of a high homogeneity. An x‐ray analysis showed that the mixed crystals thus prepared were uniform within 0.01‐mole fraction.