Liu, T.-A.T.-A.LiuPan, C.-L.C.-L.PanGONG-RU LIN2018-09-102018-09-10200100214922http://www.scopus.com/inward/record.url?eid=2-s2.0-0036155401&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/293523A pump-probe study of GaAs grown by molecular beam epitaxy at low temperatures (LT-GaAs) is performed. Ultrashort carrier lifetimes of the as-grown LT-GaAs increase from <0.13 ps (measurement limitation) to 1.8±0.2 ps as the growth temperature is increased from 200°C to 320°C. The carrier lifetime was found to be approximately inversely proportional to the antisite defect concentration. This trend is found to be in reasonably good agreement with the Schokley-Read-Hall model. The decreasing trend in the amplitudes of continuous-wave and transient reflectivities (ΔR/R) as a function of the growth temperature for the LT-GaAs is explained as an induced absorption caused by dense arsenic antisite defects. The sign of the transient ΔR/R reversed for LT-GaAs grown at 200°C. This is tentatively attributed to the band gap renormalization effect.Carrier lifetime; Defect; LT-GaAs; MBE; Photo-reflectivity; Pump-probe; UltrafastCarrier concentration; Carrier mobility; Energy gap; Hot carriers; Low temperature operations; Mathematical models; Molecular beam epitaxy; Optical properties; Point defects; Solid state lasers; Spectroscopy; Ultrafast phenomena; Band gap renormalization effect; Carrier lifetime; Defect concentration; Dense arsenic antisite defect; Low temperature gallium arsenide; Optical reflectivity spectroscopy; Pump-probe; Shockley-Read-Hall model; Time resolved photoreflectivity; Semiconducting gallium arsenidejournal article10.1143/jjap.40.62392-s2.0-0036155401