標題: Microstructure and subpicosecond photoresponse in GaAs grown by molecular beam epitaxy at very low temperatures
作者: Chin, A
Chen, WJ
Ganikhanov, F
Lin, GR
Shieh, JM
Pan, CL
Hsieh, KC
電子工程學系及電子研究所
光電工程學系
Department of Electronics Engineering and Institute of Electronics
Department of Photonics
公開日期: 15-七月-1996
摘要: Cross-sectional transmission electron microscopy (TEM) and femtosecond (fs) reflectivity are used to study (Ga,As) compound grown at low temperatures from 160 to 70 degrees C, A columnar polycrystalline GaAs is observed for samples grown at 160 degrees C while it appears amorphous for samples grown at temperatures below 120 degrees C, The successful growth of amorphous (Ga,As) at 70 degrees C, instead of a mixture of metallic Ga droplets and As solids, suggests that the decomposition of As-4 molecules may be catalyzed by the surface Ga. Upon annealing, all samples become polycrystalline before epitaxial solid state regrowth eventually dominates and the whole sample becomes single crystal for long enough annealing. Carrier lifetime of 230 fs is measured for the as-grown amorphous sample. For the annealed sample, the photoresponse exhibits a fast initial decay of 120 fs and a much slower secondary decay of 33 ps. The initial decay is attributed to the formation of fine polycrystalline grains (similar to 500 Angstrom in size) whose grain boundaries provide effective carrier traps and recombination centers. (C) 1996 American Institute of Physics.
URI: http://hdl.handle.net/11536/1160
ISSN: 0003-6951
期刊: APPLIED PHYSICS LETTERS
Volume: 69
Issue: 3
起始頁: 397
結束頁: 399
顯示於類別:期刊論文