Autodoping Effects of Ge in Vapor-Grown GaP Layers on Ge Substrates

The autodoping effects of Ge incorporated into the GaP layer grown via vapor‐phase transport on Ge substrate are investigated at 300°K. XMA and point‐contact‐breakdown techniques are used to obtain the free‐carrier concentration profiles across the grown layer. The free‐carrier concentration is found not to exceed 1.3×10¹⁷ cm⁻³ because of self‐compensation of Ge donor acceptors. The compensation ratio $N_A^{-}{\mathrm{+N}}_D^{+}$ reaches up to 90% above 5×10¹⁷ cm⁻³ of ${\mathrm{|N}}_A^{-}{\mathrm{+N}}_D^{+}|$ , where $N_A^{-}$ and $N_D^{+}$ represent the ionized Ge acceptor and donor concentration, respectively. Considering various scattering mechanisms, ionization rates of the Ge atoms incorporated into the GaP layer are deduced. The emission spectra from zinc‐diffused p‐n junctions fabricated with these GaP layers also reveal strong dependence upon the Ge concentration. Their intensity variation is satisfactorily explained by the pair model. The correlation between the emission intensity of the Zn–Ge pair band and the injection efficiency of an electron is discussed as well as the correlation between that of the Ge–Ge band and $N_A^{-}{\mathrm{/N}}_D^{+}$ .