Ho Ching-Hwa
Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
ACS Omega. 2020 Jul 15;5(29):18527-18534. doi: 10.1021/acsomega.0c02623. eCollection 2020 Jul 28.
Direct band edge is a crucial factor for a functional chalcogenide to be applied in luminescence devices, photodetectors, and solar-energy devices. In this work, the room-temperature band-edge emission of III-VI GaSe has been first observed by micro-photoluminescence (μPL) measurement. The emission peak is at 1.85 eV, which matches well with the band-edge transition that is measured by micro-thermoreflectance (μTR) and micro-transmittance (μTransmittance) for verification of the direct band edge of GaSe. The temperature-dependent μTR spectra of GaSe show a general semiconductor behavior with its temperature-energy shift following Varshni-type variation. With the well-evident direct band edge, the peak responsivities of photovoltaic response (∼6.2 mV/μW) and photocurrent (∼2.25 μA/μW at = 30 Hz) of defect zincblende GaSe can be, respectively, detected at ∼2.22 and ∼1.92 eV from a Cu/GaSe Schottky solar cell and a GaSe photoconductor. On the basis of experimental analysis, the optical band edge and photoresponsivity properties of a III-VI GaSe defect semiconductor are thus realized.
直接带隙边缘是功能硫族化物应用于发光器件、光电探测器和太阳能器件的关键因素。在这项工作中，首次通过微光致发光（μPL）测量观察到了III-VI族GaSe在室温下的带隙边缘发射。发射峰位于1.85 eV，这与通过微热反射（μTR）和微透射率（μTransmittance）测量的带隙边缘跃迁很好地匹配，以验证GaSe的直接带隙边缘。GaSe的温度依赖μTR光谱显示出一般的半导体行为，其温度-能量偏移遵循Varshni型变化。由于具有明显的直接带隙边缘，从Cu/GaSe肖特基太阳能电池和GaSe光电导体中，分别在约2.22 eV和约1.92 eV处检测到缺陷闪锌矿GaSe的光伏响应（约6.2 mV/μW）和光电流（在 = 30 Hz时约2.25 μA/μW）的峰值响应率。基于实验分析，从而实现了III-VI族GaSe缺陷半导体的光学带隙边缘和光响应特性。
