Study of MBE growth for extended blue photocathode window layer

Abstract

ABSTRACT We report growth of high Aluminum content and heavy P type doping AlGaAs by molecular beam epitaxy (MBE) for extended blue photocathode window layer. The key factors which affect of extended blue photocathode window AlGaAs layer during epitaxy growth were analyzed and show that growth conditions such as V/III flux ratioe substrate temperature and growth rate have dramatically effected on the AlGaAs layer crystalline quality and morphology. On the basis of the optimized V/III flux ratio and appropriate growth rate, the substrate temperature for sample growth was adjusted, the P type heavy doping( • 5×10 18 cm -3 ) and large area AlGaAs single crystal material with excellent crystalline quality and good luminescence properties was fabricated on GaAs (100) substrate. The morphology of the samples was checked by high resolution optical microscopy. The crystalline quality of samples was measured by X-ray diffraction and luminescence property was measured by integral luminescence system. The relationship of the crystalline quality and substrate temperature was got. The excellent crystalline quality AlGaAs layer obtained have been applied to GENIII photocathode windows layer and spectral response range of photocathode extended to blue-green light in short wave. The Quantum efficiency in the blue-green wave range of GENIII photocathode is enhanced. Key words: AlGaAs; MBE; Photocathode; Spectral response