物理气相传输法生长1英寸AlN单晶及其表征分析

Characterization of 1 inch AlN Single Crystal Wafers Grown by PVT Method

本文采用物理气相传输法(PVT)及同质外延工艺,在自发生长的6 mm×7 mm AlN籽晶片上,通过4次迭代,成功生长出高质量1英寸AlN单晶锭。将生长出的单晶锭经过切片、研磨和抛光工艺加工成1英寸低表面粗糙度的单晶片,并采用拉曼光谱仪、扫描电子显微镜、高分辨率X射线衍射仪、分光光度计对籽晶片与外延晶片进行结晶质量、位错密度以及紫外透光率等性能表征。结果表明:外延晶片的拉曼E2(high)半高宽为2.86 cm^-1,(002)面XRD摇摆曲线半高宽为241 arcsec,说明晶片具有很高的结晶质量;经过同质外延4次迭代后的晶片较初始籽晶片相比质量有所下降,说明生长过程中由于非平衡生长存在缺陷的增殖;外延晶片具有极其优异的紫外透光率,深紫外265~280 nm波段下的吸收系数低至19~21.5 cm^-1。

In this work,1 inch bulk AlN single crystals were homoepitaxially grown by the physical vapor transport method based on a 6 mm×7 mm freestanding AlN seed after 4 iterations.The single crystals were sliced into wafers and then lapped/polished following the common wafering standards.The obtained wafers were characterized by Raman spectroscopy,high resolution X-ray diffraction(HRXRD),Scanning electron microscopy(SEM)and UV-Visible spectrophotometer.The Raman spectroscopy exhibits an E2(high)full width at half maximum(FWHM)of 2.86 cm^-1.The symmetric HRXRD rocking curves have the FWHMs of 241 arcsec.The quality of the homoepitaxially grown crystals is slightly lower than the first-generation AlN seed,which indicates that defects were generated due to non-equilibrium growth conditions during the homoepitaxial growth processes.Furthermore,the optical transmission spectra data reveales that the entire wafers exhibit excellent UV transparency with the absorption coefficient of 19-21.5 cm^-1 in the UV range of 265-280 nm.