CHARGE-EXCHANGE PROCESSES IN TITANIUM-DOPED SAPPHIRE CRYSTALS .1. CHARGE-EXCHANGE ENERGIES AND TITANIUM-BOUND EXCITONS

被引:80
作者
WONG, WC
MCCLURE, DS
BASUN, SA
KOKTA, MR
机构
[1] RUSSIAN ACAD SCI,AF IOFFE PHYSICOTECH INST,ST PETERSBURG 194021,RUSSIA
[2] UNION CARBIDE CHEM & PLAST CO INC,WASHOUGAL,WA 98671
来源
PHYSICAL REVIEW B | 1995年 / 51卷 / 09期
关键词
D O I
10.1103/PhysRevB.51.5682
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The photoionization of Ti3+ in sapphire -Al2O3 was studied by means of one-step and two-step photoconductivity measurements. An absorption band of Ti3+ at 2700 was shown to be due to a Ti3+ localized exciton. One-photon photoconductivity begins at the high-energy side of this band and thus the photoionization threshold can be located at 4.71 0.07 eV. The two-photon photoconductivity spectrum is nearly coincident with the excited state absorption and is shifted 0.6 eV to higher energy than the one-photon spectrum, due to the effect of the Jahn-Teller distortion of the 2E initial state. The origin of the transition due to valence band electron capture by Ti4+ is located at 4.17 eV. These electron and hole ionization energies are compared to values obtained by Born cycle calculations. Their sum is 0.5 eV less than the band gap of Al2O3. © 1995 The American Physical Society.
引用
收藏
页码:5682 / 5692
页数:11
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