Electroluminescence behavior of ZnO/Si heterojunctions: Energy band alignment and interfacial microstructure

n-ZnO/p-Si heterojunction light-emitting diodes (LEDs) show weak defect-related electroluminescence (EL). In order to analyze the origin of the weak EL, the energy band alignment and interfacial microstructure of ZnO/Si heterojunction are investigated by x-ray photoelectron spectroscopy. The valence band offset (VBO) is determined to be 3.15 +/- 0.15 eV and conduction band offset is -0.90 +/- 0.15 eV, showing a type-II band alignment. The higher VBO means a high potential barrier for holes injected from Si into ZnO, and hence, charge carrier recombination takes place mainly on the Si side rather than the ZnO layer. It is also found that a 2.1 nm thick SiOx interfacial layer is formed at the ZnO/Si interface. The unavoidable SiOx interfacial layer provides to a large number of nonradiative centers at the ZnO/Si interface and gives rise to poor crystallinity in the ZnO films. The weak EL from the n-ZnO/p-Si LEDs can be ascribed to the high ZnO/Si VBO and existence of the SiOx interfacial layer.

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Made available in DSpace on 2010-05-24T07:16:08Z (GMT). No. of bitstreams: 1 Electroluminescence behavior of ZnOSi heterojunctions Energy band alignment and interfacial microstructure.pdf: 393729 bytes, checksum: aa7b7bcdb2a6e67e684677feb0ff0006 (MD5) Previous issue date: 2010

"863" project of China 2009AA03Z305 National Natural Science Foundation of China 60876031

国际

"863" project of China 2009AA03Z305 National Natural Science Foundation of China 60876031