Optical bandgap and near surface band bending in degenerate InN films grown by molecular beam epitaxy
Optical bandgap and near surface band bending in degenerate InN films grown by molecular beam epitaxy
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DOI：
10.1063/1.4824823
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发表时间：
2013-10
影响因子：
3.2
通讯作者：
Malleswararao Tangi;Jithesh Kuyyalil;S. M. Shivaprasad
中科院分区：
文献类型：
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作者：
Malleswararao Tangi;Jithesh Kuyyalil;S. M. Shivaprasad
我们研究了 InN 薄膜上的表面电荷积累，它强烈影响载流子的迁移率。这些薄膜通过MBE在温度范围（400-470°C）下形成，产生具有不同形态、结晶度和光学特性的薄膜。根据 Moss-Burstein 关系，通过光学吸收和 PL 研究确定的带隙值取决于霍尔载流子浓度。通过分别使用 X 射线光电子能谱和光吸收测量了解相对于价带最大值的表面和体费米能级位置，可以测量 InN 薄膜上近表面能带弯曲的幅度。研究表明，由于薄膜上的In吸附层而产生表面电荷，导致低带隙单晶薄膜的能带弯曲高达1 eV，而对于高度简并的多晶薄膜，能带弯曲接近平坦。当体载流子浓度与晶体质量相关时，会出现能带弯曲的缺失。
We study the surface charge accumulation on InN thin films that strongly effects mobility of charge carriers. The films are formed by MBE in the temperature range (400–470 °C) yielding films with different morphology, crystallinity, and optical properties. The band-gap values determined by optical absorption and PL studies are found to depend on the Hall carrier concentration as per the Moss-Burstein relation. The magnitude of the near surface band bending is measured on InN thin films by knowing the surface and bulk Fermi level position with respect to the valence band maximum using X-ray photoelectron spectroscopy and optical absorption measurements, respectively. The studies show that the surface charge occurs due to the In adlayer on the film causing band-bending is up to 1 eV for low band gap single crystalline films and nearly a flat band for the highly degenerate polycrystalline films. The absence of the band bending is seen to occur when the bulk carrier concentration related to the crystalline qu...