【摘要】 用光电导测定厚度为４～３０μｍ的未掺杂ＧａＡｓＭＯＣＶＤ外延层中自由激子跃过特性．发现当外延层厚度增加时，结合能Ｒｘ增大，ｎ＝１自由激子峰位略向低能区漂移，而激子的高激子态强度和寿命τ都减小，这些效应主要归因于外延层表面的缺陷和电场的作用，最后，讨论了光致发光结果和测量温度对它的影响．更多还原

【Abstract】 he properties of the free-exciton transitions in undoped MOCVD GaAs epitaxial layer of thicknesses varying from 4 to 30 Urn were determined by using the photoconductivity measurements.It was found that as the thickness is increased,the binding energy R.increases,and the free exciton peak for n=1 shifts slightly towards lower energies,but both the intensity of the higher excitonic levels and the lifetime T of the excitons decrease.These effects were attributed mainly to the defects and electrical field near the surface of the epilayer.Finally,the photoluminescence results and the influence of the measurement temperature on them were also discussed.更多还原