Optimization of optical properties of graded-xAlxGa1-xAs window layers on LPE-grown GaAs solar cells
GaAs solar cells grown by the liquid phase epitaxy (LPE) etchback regrowth method were respect to their graded-x AIxGa1-xAs window layer and their antireflection coatings. In a theoretical multilayer model which makes use of the matrix transfer method with complex optical constants the graded-x layer was simulated by sublayers of different x. lt was found that graded-x layers are superior to constant-x window layers. Experimental results from various AR layer systems applied to the LPE solar cells are in good agreement with the theoretical predictions. The best solar cell of 1 x 1 square cm area showed an one-sun efficiency of 23.3 % (AM 1.5).