Optical studies of ion-bombarded gallium arsenide

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6068746

Feng, G

The present work studies the disorder in ion-implanted and ion-etched GaAs semiconductors. The primary targets in this study consist of two types of systems: 45-keV Be{sup +}-implanted GaAs and low-energy Ar{sup +}-etched GaAs. Electronic and lattice structural disorder in these systems are investigated by means of optical reflectivity measurements and Raman-scattering techniques. Visible-ultraviolet reflectivity measurements have identified finite-size effects on the interband electronic excitations in microcrystalline GaAs ({mu}-GaAs), which is known from previous work to exist in Be{sup +} implanted disordered GaAs. The optical properties of {mu}-GaAs differ appreciably from those of the bulk crystal, the difference increasing with L{sup {minus}1}, the inverse of the characteristic size of the microcrystals. A simple theory is proposed which semi-quantitatively accounts for the observed size effects. Small microcrystal size implies a short time for an excited carrier to reach and to be scattered by, the microcrystal boundary, thus limiting the excited-state lifetime and broadening the excited-state energy. An alternative uncertainty-principle argument is also given in terms of the confinement-induced k-space broadening of electron states. The near-surface structural disorder in Ar{sup +}-etched GaAs has been investigated using a combination of Raman scattering and optical reflectivity measurements. The longitudinal optical (LO) Raman mode in the ion-damaged medium preserves its crystalline lineshape, indicating that the crystalline long-range order is retained in the disordered structure. The structural damage is depth-profiled with LO Raman intensity measurements together with wet chemical etching.

• Research Organization: Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (USA)
• OSTI ID: 6068746
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360605* -- Materials-- Radiation Effects
656003 -- Condensed Matter Physics-- Interactions between Beams & Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ARGON IONS
ARSENIC COMPOUNDS
ARSENIDES
BERYLLIUM IONS
CHARGED PARTICLES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELECTROMAGNETIC RADIATION
ELECTRONIC STRUCTURE
ETCHING
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
ION IMPLANTATION
IONS
MATERIALS
MATHEMATICAL MODELS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PHYSICAL RADIATION EFFECTS
PNICTIDES
RADIATION EFFECTS
RADIATIONS
REFLECTIVITY
SEMICONDUCTOR MATERIALS
SURFACE FINISHING
SURFACE PROPERTIES
ULTRAVIOLET RADIATION
VISIBLE RADIATION