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获得高量子效率且稳定性良好的阴极一直是近年来发展GaAs光电阴极的重要方向。对晶面为(100),掺杂Be,厚度为1μm分子束外延生长的反射式GaAs发射层,设计了一种从体内到表面掺杂浓度由高到低分布的新型梯度掺杂结构。掺杂浓度的范围从1×1019cm-3到1×1018cm-3,并利用(Cs,O)激活技术制备了GaAs光电阴极。光谱响应测试曲线显示,与传统均匀掺杂的GaAs光电阴极相比,梯度掺杂的GaAs光电阴极的量子效率在整个波段都有提高,积分灵敏度可达1580μA/lm,且具有更好的稳定性。讨论了这种新型GaAs光电阴极获得更高量子效率的内在机理。该设计结构是现实可行的,且具有很大发展潜力,它为国内发展高性能GaAs光电阴极提供了一条重要途径。
To obtain high quantum efficiency and good stability of the cathode has been an important direction in the development of GaAs photocathode in recent years. A novel gradient doping structure with high (100%), Be doped and 1 μm thickness molecular beam epitaxy was designed. The doping concentration ranged from 1 × 10 19 cm -3 to 1 × 10 18 cm -3. GaAs photocathodes were prepared by (Cs, O) activation technique. The spectral response curves show that the quantum efficiency of gradient-doped GaAs photocathodes increases over the whole wavelength range compared with that of the conventional uniformly doped GaAs photocathodes. The integral sensitivity is up to 1580μA / lm with better stability . The intrinsic mechanism of higher quantum efficiency for this new GaAs photocathode is discussed. The design structure is realistic and has great potential for development. It provides an important way for the development of high performance GaAs photocathode in China.