锗酸铋晶体光电导性质的研究

生长了六种掺杂锗酸铋(简称 BGO)晶体(分别掺 Fe、Cr、Mn、W、Pb 和 Ce)。在合适的测试条件下,测量了它们的光吸收系数、光电导参数和暗电导率,并与未掺杂样品进行了比较。计算出了样品的特征参量μφτ,为上述材料光折变性质的研究提供了必不可少的数据。在此基础上,对 BG0∶Cr、BGO∶Fe 和BGO∶Mn 晶体的光折变机制进行了简略的讨论,认为 BGO∶Cr 中的光折变中心可能是:Cr~(3+)作为施主,Cr~(4+)作为电子陷阱;或 Cr~(4+)作为受主,Cr~(3+)为空穴陷阱。

Study of Photoconduction Properties of Bi_4Ge_3O_(12) Crystals

Six kinds of doped-Bi_4Ge_3O_(12) (BGO) crystals,including Fe,Cr,Mn,W,Pband Ce as dopants respectively,have been grown by the Bridgeman technigue.Theoptical absorption coefficients,dark,conductivities and photoconduction parametersof these doped BGO crystals were measured and compared with undoped BGO.Itwas found that the experimental conditions such as wavelength ahd intensity ofincident light beam used for photocurrent measurement and pretreatment of the investig-ated samples have great influence on the experimental results.On the basis ofthe fact,we have fixed the suitable experimental conditions which reducethe disturbance from oneself to the minimum.Thus the experimental data of theoptical absorption coefficients,dark conductivities and photoconduction parametersobtained in the present study would be independent on the experimental conditions.Based on these data,the mechanisum of photorefractive effect in Cr-doped BGO,Fe-doped BGO and Mn-doped BGO crystals are briefly discussed.It is considered thatphotorefractive centers in the Cr-doped.BGO.may be either Cr~(3+) as donor and Cr~(4+)as electron trap,or Cr~(4+) as acceptor and Cr~(3+) as hole trap.