Photoelectric Properties of GaS_1-Se (0 ≤ x ≤ 1) Layered Crystals

In this study, the photoelectric properties of a complete series of GaS_1-Se (0 ≤ x ≤ 1) layered crystals are investigated. The photoconductivity spectra indicate a decreasing bandgap of GaS_1-Se as the Se composition x increases. Time-resolved photocurrent measurements reveal a significant improvement in the response of GaS_1-Se to light with increasing x. Frequency-dependent photocurrent measurements demonstrate that both pure GaS crystals and GaS_1-Se ternary alloy crystals exhibit a rapid decrease in photocurrents with increasing illumination frequency. Crystals with lower x exhibit a faster decrease in photocurrent. However, pure GaSe crystal maintains its photocurrent significantly even at high frequencies. Measurements for laser-power-dependent photoresponsivity and bias-voltage-dependent photoresponsivity also indicate an increase in the photoresponsivity of GaS_1-Se as x increases. Overall, the photoresponsive performance of GaS_1-Se is enhanced with increasing x, and pure GaSe exhibits the best performance. This result contradicts the findings of previous reports. Additionally, the inverse trends between bandgap and photoresponsivity with increasing x suggest that GaS_1-Se-based photodetectors could potentially offer a high response and wavelength-selectivity for UV and visible light detection. Thus, this work provides novel insights into the photoelectric characteristics of GaS_1-Se layered crystals and highlights their potential for optoelectronic applications.