Electrical and deep levels characteristics of ZnO/Si heterostructure by MOCVD deposition

ZnO films have been prepared on p-type Si substrates by metal-organic chemical vapour deposition (MOCVD) at different total gas flow rates. The current versus voltage and temperature (I-V-T) characteristics, the deep-level transient spectroscopy (DLTS) and the photoluminescence (PL) spectra of the samples were measured. DLTS shows two deep-level centres of E_1 (E_\rm C--0.13\pm 0.02\,eV) and E_2 (E_\rm C--0.43\pm 0.05 eV) in sample 1202a, which has a ZnO/p-Si heterostructure. A deep level at E_\rm C--0.13\pm 0.01 eV was also obtained from the I-T characteristics. It was considered to be the same as E_1 obtained from DLTS measurement. The emission related to this deep level center was detected by PL spectra. In addition, the energy location and the relative trap density of E_1 was varied when the total gas flow rate was changed.