Structural, compositional, and optoelectronic properties of thin-film CdS on p-GaAs prepared by pulsed-laser deposition

Thin-film CdS (300–400 nm) was deposited onto p-GaAs with low-temperature pulsed-laser deposition (PLD) using 532 nm emission of a Nd:YAG laser (6 ns, 10 Hz). The ablation threshold takes place at a fluence of 0.64 J/cm2 and the deposition rate reaches its maximum at 2.68 J/cm2, while further fluence increase caused a deposition rate drop due to plume shielding. X-ray investigations illustrated that the CdS film texture is composed of nano-sized crystallites (10–30 nm) embedded in an amorphous matrix. Energy dispersive analysis of X-ray and electron probe microanalysis revealed almost stoichiometric composition. Alternating photocurrent spectroscopy showed that the CdS/GaAs sample exhibits intrinsic room-temperature responsivity, which might be useful for specific optoelectronic interconnects. The work emphasizes versatility and straightforwardness of PLD to form operative devices based on hetero-pairing.