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氧化锌(ZnO)是一种直接带隙半导体材料,室温下带隙为3.37eV,激子束缚能为60meV。ZnO因其优越的光电特性在高亮度蓝紫光发光器件、紫外探测器件和短波长激子型激光器等方面具有广阔的应用前景。而要实现大功率的光电器件,稳定可靠的欧姆接触是必需的。研究了氮气氛条件下,不同温度快速退火对氮掺杂ZnO样品的电学性质以及Ni/Au与其接触特性的影响。原生样品表现为弱的肖特基接触,适当温度退火后,由肖特基转成了欧姆接触,650℃退火后得到最小比接触电阻率8×10-4Ω·cm2。霍尔测量表明550℃快速退火后,样品的导电类型由p型转变成了n型。采用AES和GXRD分别研究了不同退火温度下Au、Ni、Zn、O的深度分布变化及退火后所生成的合金相。实验结果表明,退火所导致的薄膜电学性质的变化以及界面态和表面态的增加是接触特性变化的原因。
Zinc oxide (ZnO) is a direct bandgap semiconductor material with a bandgap of 3.37 eV at room temperature and an exciton binding energy of 60 meV. ZnO has broad application prospects in the fields of high brightness blue-violet light-emitting devices, ultraviolet detection devices and short-wavelength exciton-type lasers because of its superior photoelectric properties. To achieve high-power optoelectronic devices, stable and reliable ohmic contact is required. The effects of rapid annealing at different temperatures on the electrical properties of Ni-doped ZnO samples and the contact characteristics of Ni / Au were investigated under nitrogen atmosphere. The primary samples showed weak Schottky contacts. After proper temperature annealing, Schottky transitions to ohmic contact, and the minimum specific contact resistivity was 8 × 10-4Ω · cm2 after annealing at 650 ℃. Hall measurements showed that after rapid annealing at 550 ° C, the conductivity type of the sample changed from p-type to n-type. The changes of the depth distribution of Au, Ni, Zn, O and the alloy phase after annealing were studied by using AES and GXRD respectively. The experimental results show that the change of the electrical properties of the thin films caused by the annealing and the increase of the interface states and the surface states are the causes of the change of the contact characteristics.