高质量硼掺杂单晶金刚石同质外延及电学性质研究

Homoepitaxial Boron Doped Single Crystal Diamond and Its Electrical Properties

突破高质量、高效金刚石掺杂技术是实现高性能金刚石功率电子器件的前提。本文利用微波等离子体化学气相沉积(MPCVD)法,以三甲基硼为掺杂源,制备出表面粗糙度0.35 nm,XRD(004)摇摆曲线半峰全宽28.4 arcsec,拉曼光谱半峰全宽3.05 cm^(-1)的高质量硼掺杂单晶金刚石。通过改变气体组分中硼元素的含量,实现了10^(16)~10^(20) cm^(-3)的p型金刚石可控掺杂工艺。随后,研究了硼碳比、生长温度、甲烷浓度等工艺条件对p型金刚石电学特性的影响,结果表明:在硼碳比20×10^(-6)、生长温度1100℃、甲烷浓度8%、腔压160 mbar(1 mbar=100 Pa)时p型金刚石迁移率达到207 cm^(2)/(V·s)。通过加氧生长可以提升硼掺杂金刚石结晶质量,降低杂质散射。当氧气浓度为0.8%时,样品空穴迁移率提升至614 cm^(2)/(V·s)。

The breakthrough of high quality and high efficiency diamond doping is the premise of realizing high-performance diamond power electronic devices.In this paper,the homoepitaxial growth of high-quality boron doped single crystal diamond was prepared by MPCVD with trimethylboron as the source gas.The surface roughness is 0.35 nm,the full width at half maximum(FWHM)of XRD(004)rocking curves is 28.4 arcsec,and the FWHM of Raman spectrum is 3.05 cm^(-1).By changing the boron concentration in the gas component,the controlled p-type diamond doping with the concentration from 10^(16) cm^(-3) to 10^(20) cm^(-3) was realized.Then,the effects of deposition conditions such as B/C ratio,growth temperature and methane content on the electrical properties of p-type diamond were studied.The hole mobility of 207 cm^(2)/(V·s)has been obtained with the B/C ratio of 20×10^(-6),the growth temperature of 1100℃,the CH_(4)/H_(2) ratio of 8%and the chamber pressure of 160 mbar.Furthermore,the crystal quality of boron doped diamond can be improved with the adding of oxygen in the gas component,that is to say,reducing the impurity scattering.When the O_(2)/H_(2) ratio is 0.8%,the hole mobility increases significantly to 614 cm^(2)/(V·s).