薄吸收区AlGaN肖特基日盲探测器在不同金属接触下的表现及机理分析

Performance and Mechanism Analysis of Thin Absorption Region AlGaN Schottky Solar-blind Detector with Different Metal Contact

摘要:

针对具备100~200nm薄吸收区的肖特基型探测器,研究了不同金属接触对其暗电流和光谱响应特性的影响。以GaN基材料为主体,在薄层Al0.42Ga0.58N表面分别制备Au和Ni/Au形成肖特基接触,在Al0.55Ga0.45N表面以Ti/Al/Ti/Au制备欧姆接触,从而制备薄吸收区的AlGaN肖特基日盲探测器。结果表明对AlGaN材料,Au肖特基型探测器的光响应良好,达到0.10A/W,外量子效率峰值为47%,但暗电流稍大,为3.91×10-10A/cm²。而Ni/Au肖特基型探测器的暗电流稳定,普遍在4.17×10-11A/cm²,而响应率一般,为0.07A/W,外量子效率为33%。测试结果与仿真模型基本一致,对正照式,受势垒高度和界面损耗层等因素影响,相较Ni/Au肖特基型探测器,Au肖特基型探测器的响应范围更大、响应率更高；对背照式,吸收层的厚度对响应范围有很大影响,薄吸收区有效展宽了响应区域。

Abstract:

For a Schottky detector with a thin absorption region of 100~200nm, the influence of different metal contacts on the dark current and spectral response characteristics was studied. Taking GaN-based materials as the main body, Au and Ni/Au were prepared on the surface of thin Al0.42Ga0.58N to form Schottky contacts, and Ti/Al/Ti/Au were prepared on the surface of Al0.55Ga0.45N to form ohmic contacts. Thus, an AlGaN Schottky solar-blind detector with a thin absorption region is fabricated. The results show that for AlGaN material, the photoresponse of Au Schottky detector is good, reaching 0.10A/W, the peak external quantum efficiency is 47%, but the dark current is slightly larger, which is 3.91×10-10A/cm². The dark current of Ni/Au Schottky detector is stable at 4.17×10-11A/cm², while the responsivity is generally 0.07A/W, and the external quantum efficiency is 33%. The test results are consistent with the simulation model. For the front irradiation mode, Au Schottky detector has a larger response range and higher responsivity than Ni/Au Schottky detector due to factors such as barrier height and interface loss layer. For the back irradiation mode, the thickness of the absorption layer has a great effect on the response range, and the thin absorption region effectively extends the response range.