太赫兹GaN SBD外延材料的应力调控及低缺陷密度控制技术研究

Study of Strain Modulation and Low Density of Defects in Control for Terahertz GaN SBD Epitaxy

采用金属有机物化学气相沉积(Metal organic chemical vapor deposition,MOCVD)技术在101.6 mm(4英寸)半绝缘SiC衬底上开展太赫兹用GaN肖特基势垒二极管(Schottky barrier diode,SBD)外延材料应力演进及缺陷密度控制的研究。提出了一种基于AlGaN过渡层的应力调控方案,实现了外延材料的应力调控;采用低温脉冲式掺杂技术生长n+-GaN层,降低了外延材料的缺陷密度,提升了晶体质量。研制的101.6 mm GaN SBD外延材料的弯曲度(Bow)/翘曲度(Warp)为-12/18μm,(002)/(102)面半高宽为148/239 arcsec,方阻9.2Ω/□,方阻片内不均匀性1.1%,并基于自研材料实现了截止频率为1.12 THz的GaN SBD器件的研制。

The stress evolution and control of defect density of terahertz GaN Schottky barrier diode(SBD)epitaxy grown on 101.6 mm(4-inch)semi-insulating SiC substrate were studied by metal organic chemical vapor deposition(MOCVD).A stress modulation scheme based on AlGaN transition layer was proposed,achieving stress well in control for GaN SBD epitaxy.Simultaneously,a pulse-doping process at a lower temperature was introduced into n+-GaN layer,which remarkably reduces density of defects and improves crystalline quality of GaN SBD epitaxy.The as-grown 101.6 mm GaN SBD epitaxy possesses a wafer bow/warp of-12/18μm,fullwidth at halfmaximum(FWHM)of(002)/(102)peaks of 148/239 arcsec,sheet resistance of 9.2Ω/□with nonuniformity in wafer of 1.1%.Finally,a GaN SBD device is fabricated based on the own epitaxy,showing a cut-off frequency up to 1.12 THz.