Improvement of quantum efficiency of super-high brightness and high spin-polarization photocathodes

利用高精度的超声质量流量控制器，应变补偿超晶格生长到90对(以前的控制器以12对为限)。因此，最初计划的技术，即在透明衬底上的粘合过程是不必要的，并且没有尝试粘合过程。此外，还提供了晶格匹配的透明衬底--ZnSe，并在此衬底上成功地生长出了GaAs体。这也表明粘接过程是不必要的。由于适当激发能量的稳定性，半导体激光器的使用成为可能。峰值偏振态的激发波长位于态密度的平坦区(770~780 nm)，量子效率提高4倍。

Using the high precision ultrasonic mass flow controller, the strain-compensated superlattice was grown up to 90-pair (using previous controller 12-pair was a limit.) . Then, the originally planned technique, i.e., the adhesion process onto a transparent substrate, was not necessary and the adhesion process was not tried. In addition to it, lattice-matching and transparent substrate, ZnSe, was available and the growth of GaAs on ZnSe was successfully conducted. This also shows that the adhesion process was not necessary. Due to the stability of the appropriate excitation energy, use of semiconductor laser became possible. The excitation wavelength at the peak polarization located at the flat region (770~780nm) of the density-of states and then the quantum efficiency increased by 4 times.