Photoluminescence Investigation of Electronic Processes in GALLIUM(0.52) INDIUM(0.48) Phosphorus
Abstract
The optical properties of Ga_{0.52 }In_{0.48}P have been investigated by the use of a number of variations of photoluminescence (PL). Ga_{0.52 }In_{0.48}P is interesting not only because of its commercial applicability in highly efficient solar cells and light emitting devices but also from a fundamental scientific standpoint as a result of its strong tendency to form an ordered structure. The extent of ordering within the small volumes (domains) where it occurs as well as the sizes of these volumes and fraction of a sample which is ordered or not ordered as well as estimates of the volume fractions ordered in the four nominally equivalent {111 } directions can be semi-quantitatively estimated by transmission electron diffraction (TED). In addition to the fact that Ga_{0.52}In _{0.48}P displays a strong tendency to order under some conditions of growth, it is also found that the band gap may vary by as much as 90 meV at constant composition, depending on conditions of growth. The band gap variation is believed to be related to ordering, although the details of the correlation have yet to be established. In this work the optical properties of a large number of samples of Ga_{0.52} In_{0.48}P have been studied as functions of growth conditions with the objective of determining how the growth conditions determine details of the microstructure by observing the influence of those microstructural changes on the optical properties. A number of variations of the PL technique were used, including excitation intensity, analysis temperature, time/frequency and microwave modulation dependence of the PL. It was determined in the course of this work that some partially ordered samples of Ga_{0.52 }In_{0.48}P, whose band gap is reduced considerably from that which is characteristic of disordered material, have a PL emission peak whose energy depends strongly on the intensity of the light with which the PL is excited. The lifetime of this emission was also found to be dependent on excitation intensity. Such behavior is typically characteristic of materials containing internal electric fields, suggesting the presence of such fields in ordered Ga_ {0.52}In_{0.48} P.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1991
- Bibcode:
- 1991PhDT........95D
- Keywords:
-
- GALLIUM INDIUM PHOSPHIDE;
- Physics: Condensed Matter