Heteroepitaxial growth of wide bandgap cuprous iodide films exhibiting clear free-exciton emission
Heteroepitaxial growth of wide bandgap cuprous iodide films exhibiting clear free-exciton emission
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DOI：
10.1063/5.0036862
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发表时间：
2021-01-04
影响因子：
4
通讯作者：
Kawasaki, M.
中科院分区：
文献类型：
--
作者：
Inagaki, S.;Nakamura, M.;Kawasaki, M.
碘化亚铜（CuI）是一种新兴的宽带隙半导体材料，具有优良的上级光学和输运性质。特别是，CuI显示出高稳定性和自由激子的大振子强度，这对于光电应用是非常有利的。然而，迄今为止报道的CuI薄膜还不是真正的单晶，含有相当大密度的杂质和缺陷。在这里，我们展示了一个戏剧性的改善，通过分子束外延生长在晶格匹配的InAs衬底上的CuI薄膜的质量。该膜被揭示为具有高晶格相干性和原子级平坦表面的单晶结构。低温光致发光谱显示出自由激子的极尖锐的发射和捕获态的被抑制的发射。在本研究中实现的高品质的CuI薄膜不仅将促进CuI薄膜的器件应用，而且还提供了前所未有的功能，卤化物半导体在原子级尖锐的异质界面。
Cuprous iodide (CuI) is an emerging wide-bandgap semiconductor of superior optical and transport properties. In particular, CuI shows high stability and large oscillator strength of free excitons that are of great advantage for optoelectronic applications. However, thin films of CuI reported so far have not been genuine single crystals, containing a sizable density of impurity and defect. Here, we demonstrate a dramatic improvement in the quality of CuI films grown by molecular beam epitaxy on a lattice-matched InAs substrate. The film is revealed to be in a single-crystal structure with high lattice coherence and an atomically flat surface. The low-temperature photoluminescence spectra exhibit extremely sharp emission from free excitons and much-suppressed emission from trapped states. The high-quality CuI films realized in the present study will not only facilitate the device application of CuI films but also provide unprecedented functionalities in halide semiconductors at the atomically sharp heterointerfaces.