Picosecond GaAs and InGaAs photoconductive switches obtained by low-temperature metal-organic chemical vapour deposition

Abstract
High-resistivity GaAs and InGaAs layers have been obtained by the MOCVD growth technique at low temperatures for the first time. The structural and physical properties of the LT-MOCVD grown GaAs layers were similar to those of annealed LT-MBE GaAs layers-they were of a high crystalline quality with mobilities reaching 2600 cm2 V-1 s-1 and had short carrier lifetimes of 50 ps. The resistivity of the LT-grown InGaAs layers was close to its intrinsic limits. Photoconductive switches with carrier lifetimes of 20 to 40 ps, long-wavelength cutoff of 1.7 mu m, breakdown voltage of 10 V for a 5 mu m gap and sensitivity reaching 0.05 A W-1 were fabricated from those layers.