No abstract

The search of the optimal absorbing layer thickness in the bottom In0.3Ga0.7As subcell of the triple-junction In0.3Ga0.7As/GaAs/In0.5Ga0.5P solar cell was carried out assisted by the Sentaurus TCAD software package, depending on the minority charge carrier lifetime in this layer. The lifetime value was set manually and it was in the range from 17 ps to 53 ns. The calculation results showed that the optimal thickness varies from 0.9 to 7.5 μm. The estimation of the efficiency contribution of the bottom In0.3Ga0.7As subcell to the given triple-junction solar cell, at various lifetime values, was made. Its value varied from 1 to 7%.

Abstract. An avalanche photodiode with a ring structure called junction termination extension (JTE) was built and tested. It has three diffused rings around the main junction to avoid early breakdown at the surface. The JTE rings have less doping than the main junction and can be built by well controlled single ion-implantation through a single mask. Avalanche photodiodes with two mm diameter active area have been have been built by implantation of boron with a dose of 2, 3, 4 and 5 x 10 12 cm -2 , followed by deep diffusion of the junction up to 14 µm. The dark current is strongly dependent on the implantation dose, decreasing with decreasing charge. For the APDs with implanted dose of 5 x 10 12 cm -2 a gain of 8 is obtained at 1120 V. The energy resolution from a 137 Cs source was measured to be 24.4% FWHM with a 2 x 2 x 2 mm3 BGO scintillator. We have also performed simulations of the gain and breakdown voltage that correlate well with the results.