Study Of Ohmic Contacts On GaN-based Materials And Related Devices

Due to its intrinsic merits, such as wide band gap, high electron saturated drift velocity, high melting point, good coefficient of thermal conductivity, anti-radiation and good chemical stability, Gallium Nitride as a direct band gap semiconductor has become the promising material for the application of short-wave light-emitting devices and high temperature, high frequency and high power electronic devices. These devices include light-emitting diode, laser diode, UV-detector, MESFET, HEMT, MODFET etc.Since 1990's, on the basis of advanced techniques of materials preparation, GaN-based LEDs and LDs were achieved successfully, and LEDs on sapphire substrates have already been commercialized. Recently GaN-based microelectronic devices attract more and more attentions. However, in our nation, the research on GaN-based microelectronic devices is in the early stage, and a great deal of vestigation is still needed to perform on separative processes of GaN devices. Due to the lack of AlGaN/GaN heterojunction materials in the country, a few researches on AlGaN/GaN were made, and the investigation on Schottky rectifiers is much less.In this paper, we first presented a comprehensive review of the research history and current status of GaN material preparation and characterizations. On the basis of that, we conducted a detailed study of ohmic contact resistivity of metal-GaN, and AlGaN-based Schottky Barrier Diode was successfully achieved. In addition, we reported polycrystalline GaN epitaxied on silica glass substrates.The main work includes three contents as followings:1, The situation of ohmic contact about Al electrode, Ti/Al electrode on n-GaN in different annealing conditions are investigated. The best contact resistivity of Ti/Al on n-GaN is calculated to be 2.17 X lO^Qcm2 by adding and taking disc method.2^ AlGaN-based SBD was made using Ti/Al and Au as ohmic contact and schottky contact respectively. For the first time , we reported the barrier height of Au/AlGaN is 1.08eV by analysis on various I-V curves under corresponding temperatures.3^ We reported oriented polycrystalline GaN on silica substrates using a new method named Ga nitridation.