Quasi‐Single Crystalline Cuprous Oxide Wafers via Stress‐Assisted Thermal Oxidation for Optoelectronic Devices
Meng Xiao, Pengbin Gui, Kailian Dong, Liangbin Xiong, Jiwei Liang, Fang Yao, Wenjing Li, Yongjie Liu, Jiashuai Li, Weijun Ke, Chen Tao, Guojia Fang
Abstract
Abstract P ‐type semiconductor cuprous oxide (Cu 2 O) offers promising optoelectronic applications such as solar cells and photodetectors owing to its considerable absorption coefficients and high carrier mobility. However, polycrystalline Cu 2 O films with low carrier mobility resulting from excessive grain boundaries and structure disorder fail to meet the demands for these optoelectronic applications. Here a stress‐assisted thermal oxidation method to fabricate p ‐type <110>‐textured quasi‐single crystalline Cu 2 O (c‐Cu 2 O) wafers with centimeter‐scale grains is developed. It is found that strain energy induced by thermal contact stress plays a critical role in crystal growth. The resultant <110>‐textured quasi‐single c‐Cu 2 O wafers exhibit excellent crystallinity with rocking curve having a low full width at half maximum of 0.022°, a low defect density of 2 × 10 11 cm −3 , a high mobility exceeding 100 cm 2 V −1 s −1 , and a long minority lifetime of 98.5 µs. Such quasi‐single c‐Cu 2 O wafers lead to efficient solar cells with an open‐circuit voltage of 0.95 V and highly responsive photodetectors with superior cycling stability. These results indicate not only the advancement of fabricating high‐quality Cu 2 O wafers upon controllable methodology but also the promising optoelectronic applications using p ‐type metal oxide semiconductors.