Chemical modulation of valence band and photoelectric properties of epitaxial p-type infrared transparent conducting CuScO2 thin films
Chemical modulation of valence band and photoelectric properties of epitaxial p-type infrared transparent conducting CuScO2 thin films
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外延p型红外透明导电CuScO2薄膜的价带化学调制及光电性能
DOI：
10.1088/2053-1591/ab78c8
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发表时间：
2019-12-01
影响因子：
2.3
通讯作者：
Yue, Dan
中科院分区：
文献类型：
--
作者：
Chuai, Ya-Hui;Bai, Yu;Yue, Dan
采用聚合物辅助沉积（PAD）法在a面蓝宝石衬底上外延生长了p型红外透明导电氧化物（TCO）CuScO 2薄膜。CuScO 2的价带（主要由本地化的O-2 p和Cu-3d轨道组成）进行化学改性，通过在O2存在下退火的薄膜，目标是使载流子空穴离域。在1%-3%O2气压下得到了c轴取向的薄膜。CuScO 2与衬底的取向关系为[3 R]（0001）//a-Al 2 O3（1 2 <$10）。传导过程遵循小极化子跳跃机制，跳跃激活能在0.032-0.51 eV范围内（取决于O2分压）。该膜表现出p型导电性。在室温下，在1%O2分压下退火的CuScO 2薄膜的电导率为22.1 S cm-1。用等于1%和3%的O2压力制备的膜在可见光和中红外区域保持其光学透明度（分别> 90%和> 75%）。据我们所知，这些是通过化学方法生产的性能最好的p型透明导电薄膜。为了证明这些薄膜的实际用途，我们制作的p-CuScO 2/n-In 2 O3异质结二极管，它显示出约2.5 V的阈值电压，这与CuScO 2的带隙值合理地同意。这些薄膜的高光学透明度和导电性使它们非常有希望用于光电子应用，其中需要从可见光到IR的宽波长范围。
Epitaxial p-type infrared transparent conducting oxide (TCO) CuScO2 thin films were grown by polymer-assisted-deposition (PAD) method on a-plane sapphire substrates. Valance band of CuScO2 (largely consisting of localized O-2p and Cu-3d orbitals) was chemically modified by annealing the films under O2 presence with the goal to delocalize carrier holes. Films with c-axis orientation were obtained at 1%–3% O2 pressure. The orientation relationship between CuScO2 and the substrate was [3 R](0001)//a-Al2O3(1 2 ¯ 10). Conduction processes followed the small-polaron hopping mechanism with the hopping activation energies in the 0.032–0.51 eV range (depending on the O2 partial pressure). The films demonstrated p-type conductivity. The conductivity of CuScO2 thin film annealed at 1% O2 partial pressure at room temperature was 22.1 S cm−1. Films prepared with O2 pressure equal to 1 and 3% retained their optical transparency (>90 and >75%, respectively) in the visible and mid-IR regions. To the best of our knowledge, these are the best performing p-type transparent conductive thin films produced by chemical methods. To demonstrate the practical usage of these films, we fabricated p-CuScO2/n-In2O3 heterojunction diodes, which showed ∼2.5 V threshold voltage, which agreed reasonably with CuScO2 bandgap value. High optical transparency and electrical conductivity of these films make them very promising for optoelectronic applications, in which wide wavelength ranges, from visible to IR, are required.