Investigation of the effects of growth temperature on the photocarrier density of low-temperature grown gallium arsenide photoconductive antenna

Abstract

We investigated the effects of varying the substrate growth temperatures (T_g) on the carrier density and its temporal change in low-temperature grown gallium arsenide (LT-GaAs) photoconductive antenna (PCA). Increasing T_g results to a higher crystalline quality, leading to higher carrier densities, ranging from from 1.51×10²⁴ m⁻³ at 200^◦ C to 2.50×10²⁴ m⁻³ at 320^◦ C. However, the carrier density saturates in the region of 260^◦C, indicating optimal performance within a Tg range of 200^◦C to 260^◦C. Moreover, decrease in the growth temperature leads to an increase in the defect concentration which results to a decrease in the carrier lifetime, consequently decreasing carrier densities from 2.55 × 10²⁴ m⁻³ at 1.17 × 10⁻¹⁷ m⁻³ to 1.50 × 10²⁴ m⁻³ at 1.57 × 10⁻¹⁷ m⁻³. These results provide significant insights into the optimization of temperature growth, and doping concentrations parameters in LT-GaAs growth for PCA fabrication and possible THz technology applications.