TiN、Ti插入层对ITO与GaN欧姆接触性能影响的研究

Influence of TiN and Ti Insertion Layer on Ohmic Contact Performance Between ITO and GaN

透明半导体铟锡氧化物(ITO)作为电极能够降低光导开关电极边缘电流集聚效应和提高脉冲激光的利用率。本文通过在ITO与GaN界面之间分别插入10 nm的Ti与TiN,研究Ti、TiN对ITO与GaN欧姆接触性能的影响。I-V测试结果表明,随着退火温度升高,插入TiN的光导开关一直保持欧姆接触特性,而插入Ti的光导开关由欧姆接触转变为肖特基接触。通过TEM测试发现,当以Ti作为插入层时,ITO通过插入层向插入层与GaN的界面扩散,在接触界面形成Ti的氧化物及空洞。透射光谱显示,不同退火温度下插入Ti层的透过率均低于38.3%,而以TiN作为插入层时透过率为38.8%~55.0%。因此含有TiN的光导开关具有更稳定的电学性能和更高的透过率,这为GaN光导开关在高温高功率领域的应用提供了参考。

The electrode made of transparent semiconductor indium tin oxide(ITO)can reduce the edge current crowding effect of photoconductive semiconductor switches and improve the utilization of pulse laser.In this paper,10 nm Ti and TiN layer were inserted into the interface between ITO and GaN,and the influences of Ti and TiN layer on the Ohmic contact performance between ITO and GaN were studied.I-V test results show that with the increase of the annealing temperature,the GaN photoconductive semiconductor switch with Ti insertion layer changes from Ohmic contact to Schottky contact,while the photoconductive semiconductor switch with TiN insertion layer keeps Ohmic contact characteristics.TEM observation shows that when Ti is used as the insertion layer,ITO diffuses through the insertion layer to the interface between the insertion layer and GaN,resulting in the formation of Ti oxide and holes at the interface.The transmission spectra show that the transmittance of samples with Ti insertion layer is less than 38.3%at different annealing temperatures,while the transmittance is 38.8%~55.0%when TiN is used as the insertion layer.Therefore,the photoconductive semiconductor switch containing TiN insertion layer shows a higher thermal stability and transmittance,which provides reference for the application of GaN photoconductive semiconductor switch in the field of high temperature and high power.