High Performance Tri-Gate InAlN/GaN High-K MOSHEMTs with Light Fluorine Dopants

Abstract

In this work we demonstrate a high performance tri-gate InAlN/GaN high-K MOSHEMTs with light fluorine dopants Next we will divide into three major points to discuss the proposed device First the device is a tri-gate nanowire structure with high work function metal and light fluorine dopants to achieve an enhancement-mode device The combination of the above three technologies can not only amplify the effect of the depleted two-dimensional electron gas through the structure of the tri-gate but also through the help of tri-gate and high work function metal gate the total amount of fluorine ions can be minimized In order to further improve the control ability of the gate we use a tri-gate structure with high-k dielectric dual oxide layers The high-k dielectric dual oxide layers have a high dielectric which can enhance the control ability of the tri-gate and further improve the performance of the device In addition the strong electric field control ability can suppress the problem of thermal stability of fluorine ions at high temperature so that the device remains highly reliable and stable at high temperature Moreover we use the Schottky drain extension structure whose function is like a drain field plate which can effectively distribute the drain electric field and increase the breakdown voltage In addition the breakdown voltage is effectively improved while the on-resistance doesn’t degrade due to Schottky drain extension with a low work function metal In this work Secondary ion mass spectroscopy (SIMS) was measured to confirm the depth distribution of fluorine ions Next in order to study the chemical element composition surface characteristics and thickness of the dual oxide layers some material analyses were carried out such as x-ray diffraction (XRD) x-ray photoelectron spectroscopy (XPS) atomic force microscopy (AFM) and transmission electron microscopy (TEM) Moreover we also conducted an atomic force microscope (AFM) analysis of the drain metal to confirm the surface roughness The device has a threshold voltage (VTH) of +0 48 V an on/off current ratio of 1010 a sub-threshold swing (SS) of 67 3 mV/ten times and an on-state current (Ion) of 810 mA/mm at The breakdown voltage (VBR) at 1μA/mm is 630 V Compared with traditional planars devices all performances have been significantly improved

Date of Award	2020
Original language	English
Supervisor	Wei-Chou Hsu (Supervisor)