Journal of Materials Science, Vol.48, No.18, 6386-6392, 2013
Nitrogen doping of ZnTe for the preparation of ZnTe/ZnO light-emitting diode
Nitrogen-doped p-type zinc telluride (p-ZnTe) films are prepared by sputtering in a mixture of nitrogen/argon plasma. The effect of doping level N (ratio of N-2 flow rate to that for the mixed gas) in the range 0-10 % on the films properties is investigated. Heterojunction diodes are prepared on stainless steel flexible substrate from the p-ZnTe (doping level, N = 5 %) and solution-grown n-ZnO films. The junction parameters and light-emission properties of diodes are investigated. Doping level beyond N = 1 %, changes the cubic crystal structure of ZnTe to hexagonal and reduces the size of crystallites. At the doping level N = 2-4 %, films with the highest hole density of 2.5 x 10(18) cm(-3) and lowest band gap energy of 1.4 eV are obtained. The diodes junction built-in potential and the donor density in n-ZnO films are found to be in the range 0.4-0.7 V and 1.5 x 10(17)-1.4 x 10(18) cm(-3), respectively. Diodes exhibit electroluminescence in the UV and visible regions due to the band edge and defect emissions in ZnO.