2005 Fiscal Year Final Research Report Summary
Study on the Optical Properties of Superlattices formed by Alloy Semiconductors
| Project/Area Number |
16540288
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Condensed matter physics I
|
|---|
| Research Institution | Wakayama University |
|---|
Principal Investigator |
SHINOZUKA Yuzo Wakayama University, Faculty of Systems Engineering, Professor, システム工学部, 教授 (30144918)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
UNO Kazuyuki Wakayama University, Faculty of Systems Engineering, Associate Professor, システム工学部, 助教授 (90294305)
|
|---|
| Project Period (FY) |
2004 – 2005
|
| Keywords | alloy semiconductor / superlattice / quantum well / III-V compound / CPA / dimensionality / XAFS / nitride |
|---|
| Research Abstract |
Electronic structures of a quantum well (QW) constructed from a binary alloy semiconductor A_<1-x>B_x are studied in the coherent potential approximation (CPA). A tight binding model is used for a single particle (electron, hole, Frenkel exciton) in the well composed by a rectangular array of N_xx N_yx N_z sites. The effects of the diagonal randomness are included as the coherent potential Σ(E), which is assumed to be the same for all sites, and is selfconsistently determined with the average Green's function. The energy density of states ρ(E) and the absorption spectrum I(E) due to a creation of a Frenkel exciton are calculated for various well-size and the dimensionality. For slab (∞,∞,N_z) and wire (∞,N_y,N_z) structures, ρ(E) and I(E) are composed of N_z (or N_yx N_z) subbands with remains of two (one)-dimensional van-Hove singularity. When x (or 1-x) is small, a B (A) impurity-band always appears at the lower (higher) energy side of the lowest (highest) host-subband.
Local atomic configurations of GaInNAs and GaInNAsSb thin films around In and Sb atoms was investigated using fluorescence extended X-ray absorption fine structure (EXAFS) spectroscopy. The increase of the number of In-N bonds in GaInNAs and the number of Ga-Sb bonds in GaInNAsSb were observed due to the thermal annealing. The change would be interpreted as the reduction of the total energy of these alloys. The experimental results were consistent with the results of ab-initio calculations.
|
