Eishi Kubota

Effects of magnetic field gradient on crystallographic properties in tin-doped indium oxide films deposited by electron cyclotron resonance plasma sputtering

Tin-doped indium oxide (ITO) films were deposited by sputtering of sintered oxide targets, employing an electron cyclotron resonance (ECR) microwave plasma system. The effects of Ar ion bombardment on crystallographic and electrical properties of the films were investigated with control of the ion energy by submagnetic field application. It was found that ion bombardment with energies lower than ~ 40 eV enhances crystallization whereas bombardment with higher energies suppresses crystallization. The surface roughness of the film was below 50 A. The smooth surface formation could be attributed to the microstructural modification arising from ion bombardment.

Isoelectronic Double Doping Effect on Dislocation Density of InP Single Crystal

A Ga+Sb doping technique is proposed for reducing the dislocation density in LEC-InP crystals. Using SSMS and SIMS measurements, effective distribution coefficients of Ga and Sb in InP are estimated to be 3.35 and 0.12, respectively. Effectiveness of uniform Ga+Sb concentration doping all along the growth direction is presented. Nearly dislocation-free InP crystals 25 mm in diameter are prepared using Ga+Sb doping concentration above 6×1018 cm-3.

Photoluminescence study of residual shallow acceptors in liquid‐encapsulated Czochralski‐grown InP

For nominally undoped InP crystals grown in silica, pBN, ceramic AlN, and pG crucibles by the liquid‐encapsulated Czochralski (LEC) technique, residual shallow acceptors are investigated by photoluminescence measurements. Mg and Ca, contained in the InP starting materials, are found to be removed due to reactions with the B2O3 encapsulant. Zn and C, of which Zn was dominant throughout the undoped crystals, are found to be residual acceptors incorporated during LEC growth. The B2O3 encapsulant is identified as one Zn contamination source.

Gettering Effects of B2O3 Encapsulant on Mg and Ca Impurities in LEC InP-Growth

Gettering effects have been investigated for doped Mg- and Ca-impurities in liquid encapsulated Czochralski (LEC)-grown InP single crystals. Impurity analyses were carried out for Mg- and Ca-doped InP starting materials, LEC-grown crystals and residual B2O3 encapsulants. It was found that Mg and Ca could be removed as oxide from the melt due to a chemical reaction with a B2O2 encapsulant during growth.

Growth temperature and phosphorus vapor pressure dependencies of Si incorporation into InP crystals in solution growth process

Electrical properties of synthesis, solute-diffusion (SSD)-grown InP bulk crystals were found to depend on growth temperature and phosphorus vapor pressure. The dependencies were investigated on the basis of thermodynamic analysis of the In-P-Si system and concluded to be caused by a reaction between silica crucible and In-P solution. It is shown that Si concentration in crystal increases nearly exponentially with a decrease in the reciprocal growth temperature and linearly with an increase in the cubic root of phosphorus vapor pressure.

Growth of high purity InP crystals under high growth temperature by synthesis, solute diffusion technique

Abstract This letter presents a study of high purity InP crystals grown at a high temperature of 1000°C by synthesis, solute-diffusion (SSD) technique. The technique employs a capillary, having an inner diameter of 1–2 mm and a length of 140 mm, as a barrier for preventing In 2 O vapor from diffusing into the lower temperature zone. The results confirm that the capillary is effective for producing high purity crystals having high Hall mobilities of mor than 10 5 cm 2 /V· at 77 K by suppressing silica crucible reduction.

LEC Growth of InP Single Crystals Using Ceramics AlN Crucible

The liquid encapsulated Czochralski technique using a ceramics AlN crucible has been investigated for the growth of InP single crystals. High purity crystals, typically having a carrier concentration of 2.2×1015 cm-3 and a Hall mobility of 30100 cm2/(Vs) at 77 K for the first-to-freeze portion, are grown without serious contamination of electrically active impurities from the crucible. Impurity analyses of the grown crystals and the B2O3 encapsulants are carried out. The results are compared with those for the crystal grown from a pBN crucible.

LEC Growth of High Purity InP Crystals by Pre-Encapsulation of Starting Material

InP crystals were grown by the liquid encapsulated Czochralski (LEC) technique, in which the starting materials in a pBN crucible were previously encapsulated with B2O3 using an outer vacuum vessel. The electrical properties throughout the LEC-grown InP crystals were improved by using the pre-encapsulated starting materials. This is due to the reduced incorporation into the crystals of impurities such as S and C, which are evaporated from carbon heater and radiation shield materials.

Proposal and demonstration of cached holographic 3D display system using photorefractive crystals

Abstract We demonstrate a new 3D display system with photorefractive crystals named “cached holographic 3D display”. This new system is based on a combination of computer-generated holographic display technology and holographic storage technology, and has the potential to become a universal way of viewing naturally looking 3D images. We use cerium doped strontium barium niobate crystals as a temporary storage medium in the system. The crystals include striations, which degrade the display resolution.

Reversible variation of donor concentrations in high-purity InP by thermal treatment

The donor concentration in high-purity InP bulk crystals was found to be reversibly changed by thermal treatment. At a level of 0.5–2.0×1015 cm−3, the concentration decreased below 340 °C and increased above 380 °C. Far-infrared photoconductivity measurements revealed that shallow donors with a binding energy of ∼7.5 meV were made to disappear and appear by low and high temperature treatment, respectively. Two possible mechanisms responsible for these phenomena are discussed in connection with the extrinsic and intrinsic donor origin. One probable mechanism is that shallow extrinsic donors, assigned to Si, are electrically passivated by some kind of defect, such as atomic hydrogen, and reactivated by low and high temperature treatment, respectively.