A nondestructive method for predicting laser emission wavelength from photocurrent spectra of GaAlAs double heterostructure wafers

Using nondestructive pressure contacts, a GaAlAs double heterostructure (DH) wafer may be operated as a solar cell. When the spectrum of the photocurrent is observed, the band edge of the active layer is clearly identifiable. A model of photocurrent in a GaAlAs DH wafer shows that a reliable measurement of the active layer band edge can be made in spite of substantial variations in spectral shape that can be caused by variations in the GaAs cap layer thickness. Using this method, the emission wavelength of a laser can be predicted to + or - 62 A with 90 percent confidence, making photocurrent spectroscopy a useful tool for characterizing wafers.