Study On The Leakage Currents In GaN-based Heterojunction

High electron mobility transistors(HEMTs)based on AlxGa1-xN/GaN heterostructures have a wide range of features for producing high frequency and high power devices because of their excellent electronic properties,high saturation electron drift velocity,and high breakdown voltage.It has an important prospects and status.However,the leakage current is still a challenging problem in HEMTs with AlxGa1-xN/GaN heterostructures,limiting its application.In this paper,the AlxGa1-xN/GaN heterostructure HEMT as the core is used to conduct detailed theoretical calculation and discussion on the source-drain leakage current caused by the roughness of the heterojunction interface and the gate leakage current caused by temperature fluctuation.First,the basic structure of AlxGa1-xN/GaN heterojunction,the source,distribution and concentration of high-density two-dimensional electron gas and the power supply voltage characteristics of an ideal AlxGa1-xN/GaN heterojunction based HEMT are introduced.The two models of AlxGa1-xN/GaN heterojunction HEMTs’ current and voltage are established,one is a reverse series diodes model,and the other is a junction field effect transistor model,and we give current-voltage relationships.Then based on the basic physical properties of AlxGa1-xN/GaN heterojunctions and the model of reverse series diodes,the gate leakage current induced by the two-dimensional electron gas thermal fluctuation in AlxGa1-xN/GaN heterojunction HEMTs is studied.In addition,being different from the leakage current mechanism related to defects,the leakage current of AlxGa1-xN/GaN heterojunction gate caused by the thermal fluctuation of two-dimensional electrons is also a kind of leakage current mechanism.Then based on the basic physical properties of AlxGa1-xN/GaN heterojunction and junction field-effect transistor model,the heterojunction interface leakage current caused by the thickness t fluctuation of AlxGa1-xN layer in AlxGa1-xN/GaN heterojunction HEMT is studied.In addition,the leakage current mechanism is different from that of other studies,the AlxGa1-xN/GaN heterojunction interface leakage current caused by the thickness t fluctuation of AlxGa1-xN layer is also a kind of leakage current mechanism.