In this work, we fabricated the transmission line model test structures of Ti/Al/Ni/Au Ohmic contact on the lattice-matched In0.17Al0.83N/GaN heterostructures, grown on the silicon and sapphire substrates respectively, and studied the temperature-dependent characteristics of the sheet resistance (R_sh) and the specific contact resistivity (ρ_SC). The ln(R_sh)-ln(T) plot has two distinct linearly dependent regions: 1) At T<200 K, the slope is close to zero, indicating the comparable impurity and phonon scattering components; 2) At T>200 K, it becomes much smaller than zero, as the phonon scattering effect becomes significant. Increasing the temperature from 100 K to 523 K, ρ_SC exhibits a typical roll-over behavior: 1) At T<350 K, a “metal-like” property is important, featuring a power-law coefficient of α∼1.95, which is ascribed to the formation of TiN protrusions across the InAlN barrier after the rapid thermal annealing; 2) At T>350 K, a thermionic field emission current model agrees well with the experimental data points, and the effective barrier heights are extracted to be about 1.21 eV and 0.81 eV for the samples on the silicon and sapphire substrates, respectively.

在这项工作中，我们在晶格匹配的 In0.17Al0.83N/GaN 异质结构上制造了 Ti/Al/Ni/Au 欧姆接触的传输线模型测试结构，分别生长在硅和蓝宝石衬底上，并研究了温度 -薄层电阻 ( R _sh ) 和特定接触电阻率 ( ρ _SC ) 的相关特性。ln( R _sh )-ln( T ) 图有两个不同的线性相关区域：1) 在T <200 K 时，斜率接近于零，表明杂质和声子散射分量相当；2) 在T>200 K，它变得远小于零，因为声子散射效应变得显着。将温度从 100 K 提高到 523 K，ρ _SC表现出典型的翻转行为：1) 在T <350 K 时，“类金属”特性很重要，其幂律系数为 α∼1.95，即归因于在快速热退火后形成跨越 InAlN 势垒的 TiN 突起；2) 在T > 350 K 时，热电子场发射电流模型与实验数据点非常吻合，并且提取出硅和蓝宝石衬底上样品的有效势垒高度分别约为 1.21 eV 和 0.81 eV。