The Research Of TCAD For AlGaN/GaN HFET

Gallium Nitride (GaN) is one of most important third generation semiconductors and a promising materials in power microwave, high temperature, optoelectronics, and radiation resistant applications due to its excellent physical properties and chemical stabilities, such as wide band gap, high electron saturated velocity, high breakdown electric field, high power density, etc. All the excellent properties make up the inherent drawbacks of the previous two generation semiconductor materials, which rapidly develops into the forefront of research at domestic and international.AlGaN/GaN heterostructure field effect transistor (HFET) is a kind of GaN device based on the AlGaN/GaN heterojunction. Comparing with the traditional MESFET transistors, AlGaN/GaN HFETs own the outstanding performances of high transconductance, high output current density and high cutoff frequency. In addition, the experiments show that GaN-based HFETs still maintain good DC characteristics in high temperature. So many thermal dissipation environments and equipments set for devices can be canceled, which reduce the whole system's volume and weight, and raise the efficiency. Because of GaN materials' high thermal conductivity, big heat capacity and higher breakdown voltage, GaN devices have high anti-voltage capacity and current density, which make GaN power devices can work under conditions of high-power.The tools used for computer simulation of AlGaN/GaN HFET is the new generation TCAD tools of Synopsys Inc., which include Sentaurus Process, Sentaurus Structure Editor, Sentaurus Device, Sentaurus Workbench, etc.The central phase is the selection and correction of physical models in Sentaurus Device for AlGaN/GaN HFET simulation. Sentaurus series TCAD tools are used for fitting with the experiment data of a sample device. The comparison with experiment results show that the tools can be used for AlGaN/GaN HFET simulation after correcting some parameters of crucial models. A number of device characteristics information of AlGaN/GaN HFET is obtained by simulation. Finally, computer simulation is used for study the influence of device characteristics with Al composition, AlGaN barrier layer thickness, strain relaxation and gate length, and a series of relation curves are obtain for analysis and discussion.The results show that increasing the Al composition and thickness of AlGaN barrier layer can improve the devices' performance. In addition, gate length is one of important structure parameters of AlGaN/GaN HFET, and shortening gate length can improve maximum drain-source saturation current density, extrinsic saturated transconductance and characteristic frequency.As far as I understand, there is no preliminary work of computer simulation studies and analysis for AlGaN/GN HFET using semiconductor device design for manufacturing tools in China. Therefore, the work makes a certain basis of the DFM for AlGaN/GaN HFET and correlative integrated circuits, the work is at the forefront in the domestic similar studies.