Lin Guijiang

Theoretical modeling of the interface recombination effect on the performance of III-V tandem solar cells

A typical GalnP/GalnAs/Ge tandem solar cell structure operating under AM0 illumination is proposed, and the current-voltage curves are calculated for different recombination velocities at both front and back-surfaces of the three subcells by using a theoretical model including optical and electrical modules. It is found that the surface recombination at the top GaInP cell is the main limitation for obtaining high efficiency tandem solar cells.

The epitaxial growth of high efficiency inverted metamorphic triple junction solar cell for CPV application

In this paper, 3J-IMM solar cells were studied in comparison with 3J-LM solar cells grown by MOCVD. The structural characteristics were studied by HRXRD, HRTEM and SIMS, which showed a high crystal quality of the metamorphic sub-cell. The solar cell performance in terms of I-V curves and EQE was investigated between the different solar cells structures. The current of the IMM solar cell is almost equal to the LM ´monitor solar cell. Under AM 1.5D, 1000 suns conditions, an Isc of 14.29 A, Voc of 3.538 V, FF of 83.9 %, and an efficiency of 42.3 % were achieved for the 3J-IMM solar cell with a chip size of 1.0 cm2, which is an absolute 2.9% higher than that of a 3J-LM solar cell in conversion efficiency. The excess current contribution from the Ge bottom cell in the 3J-LM solar cells is eliminated, accompanied with a 0.3V increase in Voc for the 3J-IMM solar cells.

Study of valence intersubband absorption in tensile strained Si/SiGe quantum wells

The hole subband structures and effective masses of tensile strained Si/Si1-yGey quantum wells are calculated by using the 6x6 k.p method. The results show that when the tensile strain is induced in the quantum well, the light-hole state becomes the ground state, and the light hole effective masses in the growth direction are strongly reduced while the in-plane effective masses are considerable. Quantitative calculation of the valence intersubband transition between two light hole states in a 7nm tensile strained Si/Si0.55Ge0.45 quantum well grown on a relaxed Si0.5Ge0.5 (100) substrates shows a large absorption coefficient of 8400 cm(-1).