Impact of thermal annealing on nonequilibrium carrier dynamics in single-crystal, freestanding GaAs mesostructures

in Semiconductor Science and Technology (2014), 29

We report on the impact of thermal annealing to carrier transport and transient, subpicosecond photoresponse of freestanding GaAs mesostructures. Our measurements included micro-photoluminescence and dark ... [more ▼]

We report on the impact of thermal annealing to carrier transport and transient, subpicosecond photoresponse of freestanding GaAs mesostructures. Our measurements included micro-photoluminescence and dark current and responsivity studies as well as optical femtosecond characterization. The fabricated GaAs mesostructures consisted of both mesowires and platelets that were integrated into coplanar striplines to form a photoconductive switch. We demonstrate that an optimized annealing process of our mesostructures, performed at 600 ◦C for 20 min, led to restoring bulklike properties of our freestanding devices. They exhibited dark currents below 600 pA at 10 V bias, responsivity of 0.2 A W−1 at 30 V, and mobility as high as 7300 cm2 V s−1. The annealed freestanding GaAs photodetectors were characterized by subpicosecond carrier relaxation dynamics with negligible trapping and a cutoff frequency of 1.3 THz. The latter characteristics make them excellent candidates for THz-bandwidth optoelectronics. [less ▲]

GaAs nanowhiskers for femtosecond photodetectors and THz emitters

in ASDAM 2012, The Ninth International Conference on Advanced Semiconductor Devices and Microsystems (2012)

Ultrafast and Highly-Sensitive Photodetectors with Recessed Electrodes Fabricated on Low-Temperature-Grown GaAs

in IEEE Photonics Technology Letters (2006), 18 (2006)(5-6), 820-822

We have fabricated and characterized ultrafast metal–semiconductor–metal (MSM) photodetectors with recessed electrodes, based on low-temperature-grown GaAs. The new recessed-electrode MSM geometry led to ... [more ▼]

We have fabricated and characterized ultrafast metal–semiconductor–metal (MSM) photodetectors with recessed electrodes, based on low-temperature-grown GaAs. The new recessed-electrode MSM geometry led to an improved electric-field distribution inside the photodetector structure and resulted in a 25% breakdown voltage and sensitivity increase with simultaneous four-fold reduction of capacitance, as compared to the identical MSM devices with planar electrodes. Time-resolved studies performed using 100-fs-duration laser pulses showed that recessed-electrode MSMs exhibited 1.0-ps-wide photoresponse transients with no slow after-pulse tails and their photoresponse time was 0.9 ps. The improved transient photoresponse parameters are the main advantages of the recessed-electrode geometry. [less ▲]