Finding the energy gap of Ga$_{1-x}$In$_{x}$As $p$–$n$ junctions on a metamorphic buffer from the photocurrent spectrum

A method for determining the $p$–$n$ junction band gap from photocurrent quantum yield spectrum is proposed and substantiated in the work. The method has been applied to Ga(1-x)In(x)As $p$–$n$ junctions grown by metal-organic vapor-phase epitaxy grown on metamorphic buffers. The difference between the band gap determined by the method and the electroluminescence spectrum maximum position did not exceed 3 meV. It is shown that the method can be used to determine the relationship between the band gap and the saturation current of Ga$_{1-x}$In$_{x}$As $p$–$n$ junctions.