Lindsey Zachary R, West Malachi, Jacobson Peter, Ray John Robert
Berry College, Department of Physics, 2277 Martha Berry Highway Northwest, Rome, Georgia 30149, United States.
Cryst Growth Des. 2022 Jul 6;22(7):4228-4235. doi: 10.1021/acs.cgd.2c00241. Epub 2022 Jun 7.
Compared to Si, GaAs offers unique material advantages such as high carrier mobility and energy conversion efficiency, making GaAs a leading competitor to replace Si on several technological fronts related to optoelectronics and solar energy conversion. Alloying the GaAs lattice with elemental In allows the direct bandgap of the resulting ternary alloy to be tuned across the near-infrared (NIR) region of the electromagnetic spectrum from ∼0.9 to 3.5 μm. However, methods of fabricating high-quality crystalline GaAs are currently limited by their high cost and low throughput relative to Si growth methods, suggesting the need for alternative low-cost routes to GaAs growth and alloying. This research documents the first instance in the literature of the electrodeposition and controlled alloying of polycrystalline In Ga As films at ambient pressure and near-room temperature using the electrochemical liquid-liquid-solid (ec-LLS) process. X-ray diffraction and Raman spectroscopy support the polycrystalline growth of (111)-oriented In Ga As films. Consistent redshifts of the GaAs-like TO peaks were observed in the Raman data as the In composition of the liquid metal electrode was increased. Optical bandgaps, determined via diffuse reflectance measurements, displayed a consistent decrease with the increase in the In composition of In Ga As films. While Raman, diffuse reflectance, and energy-dispersive X-ray spectroscopy data support controlled alloying efforts, all techniques suggest an overall decrease of the In/Ga ratios present in deposited films relative to those of the liquid metal electrodes. These results lend support for the continued development of ec-LLS as a viable method of achieving crystalline growth and alloying of binary and ternary semiconductor material systems using a benchtop setup under ambient pressure and near-room temperature.
与硅相比，砷化镓具有独特的材料优势，如高载流子迁移率和能量转换效率，这使得砷化镓在与光电子学和太阳能转换相关的多个技术领域成为替代硅的主要竞争者。将砷化镓晶格与元素铟合金化，可使所得三元合金的直接带隙在电磁光谱的近红外（NIR）区域（约0.9至3.5μm）内进行调节。然而，目前高质量晶体砷化镓的制造方法受到其相对于硅生长方法的高成本和低产量的限制，这表明需要替代的低成本砷化镓生长和合金化途径。本研究记录了文献中首次使用电化学液-液-固（ec-LLS）工艺在常压和近室温下电沉积和控制多晶铟镓砷薄膜合金化的实例。X射线衍射和拉曼光谱支持（111）取向的铟镓砷薄膜的多晶生长。随着液态金属电极中铟成分的增加，在拉曼数据中观察到类砷化镓TO峰的一致红移。通过漫反射测量确定的光学带隙随着铟镓砷薄膜中铟成分的增加而呈现出一致的降低。虽然拉曼、漫反射和能量色散X射线光谱数据支持控制合金化的努力，但所有技术都表明，相对于液态金属电极，沉积薄膜中铟/镓比率总体下降。这些结果支持了ec-LLS作为一种可行方法的持续发展，该方法可在常压和近室温下使用台式装置实现二元和三元半导体材料系统的晶体生长和合金化。
