Ye Jiandong

High-quality ZnO growth, doping, and polarization effect

The authors have reported their recent progress in the research field of ZnO materials as well as the corresponding global advance. Recent results regarding (1) the development of high-quality epitaxy techniques, (2) the defect physics and the Te/N co-doping mechanism for p-type conduction, and (3) the design, realization, and properties of the ZnMgO/ZnO hetero-structures have been shown and discussed. A complete technology of the growth of high-quality ZnO epi-films and nano-crystals has been developed. The co-doping of N plus an iso-valent element to oxygen has been found to be the most hopeful path to overcome the notorious p-type hurdle. High mobility electrons have been observed in low-dimensional structures utilizing the polarization of ZnMgO and ZnO. Very different properties as well as new physics of the electrons in 2DEG and 3DES have been found as compared to the electrons in the bulk.

Simulation and Suppression of the Gas Phase Pre-reaction in Metal-Organic Chemical Vapor Deposition of ZnO

The reaction mechanism and simulations of the metal-organic chemical vapor deposition reactor for ZnO film growth are presented, indicating the temperature of the reaction species. The gas phase pre-reaction can be modulated by several factors or conditions. Simulations verify the relationships between temperature and pyrolysis of precursors, and further reveal that the substrate temperature and flow rate of cooling water have great impacts on the temperature distribution. The experimental results agree with the simulations.

First-Principles GGA+U Study of Intermediate-Band Characters from Zn1−xMxO (M = 3d Transition-Metal) Alloys Suitable for High Efficiency Solar Cell*

The electronic structure characters are calculated for the Zn1−xMxO alloys with some Zn atoms in ZnO substituted by 3d transition-metal atoms (M), in order to find out which of these alloys could provide an intermediate band material used for fabricating high efficiency solar cell. Especially, among of these alloys, the electronic structure character and optical performance of Zn1−xCrxO alloys clearly show an intermediate band filled partially and isolated from the VB and the CB in energy band structure of ZnO host, and the intermediate band characters can be preserved with increasing Cr concentrations no more than 8.33% in Zn1−xCrxO alloys, at the same time, the ratio 0.52 of EgFC to EgVF in Zn1−xCrxO, (x = 4.16%) alloy is closest to the optimal ratio of 0.57. Besides, compared to the ZnO, the optical absorption does indicate a great improved absorption below the calculated band gap of the ZnO and an enhancement of the optical absorption in the whole solar spectral energy range.