γ辐照室温短波HgCdTe光伏器件的导纳谱研究

GAMMA IRRADIATION ON ROOM TEMPERATURE SHORT WAVELENGTH HgCdTe PHOTOVOLTAIC DEVICE STUDIED BY ADMITTANCE SPECTROSCOPY 

利用变频导纳谱研究了γ辐照前后Ｈｇ１－ｘＣｄｘＴｅ（ｘ＝０６）ｎ＋ｏｎｐ结中的深能级缺陷．辐照前其缺陷能级位置在价带上０１５ｅＶ，俘获截面σｐ＝２９×１０－１８ｃｍ２，缺陷密度Ｎｔ＝６５×１０１５ｃｍ－３，初步认为是Ｈｇ空位或与其相关的复合缺陷；经过１０４Ｇｙ的γ辐照后其能级变得更深，在价带上０１９ｅＶ，同时其俘获截面增加了近一个数量级，而缺陷密度基本上没有变化．γ辐照引入的这种能级变化最终使器件的性能（探测率）下降了１／２以上．

Abstract Admittance Spectroscopy (AS) measurements have been performed on n + on p Hg 1-x Cd x Te( x =0.6) photodiodes.Before gamma irradiation,a deep level located 0.15eV above the valence band is observed,its trap density N t=4.8×10 15 cm -3 with the capture cross section of approximately 2.2×10 -17 cm 2,which is probablely induced by a compound defect correlated with Hg vacancy.After 10 4Gy gamma irradiation,a new trap center located 0.19eV above the valence band is found,and the pre irradiation trap level 0.15eV above the valence band is no longer seen.The trap densities for these two levels are almost the same.This defect level change ultimately makes the device performance deteriorated.