The diagram of $p$–$n$ junction formed on the $n$-GaAs surface by 1.5 keV Ar$^+$ ion beam

The core-level and valence band electronic structure of the $n$-GaAs (100) has been studied by synchrotron-based high-resolution photoelectron spectroscopy after irradiation by an Ar$^+$ ion beam with energy $E_i$ = 1500 eV and fluence $Q$ = 1 $\cdot$ 10$^{15}$ ions/cm$^2$. Conversion of the conductivity type of the surface layer and formation of a $p$–$n$ structure have been observed. The $p$-surface layer thickness ($d\sim$ 5.0 nm) and band structure were experimentally determined from the Ga3d photoelectron spectrum by separation and analysis of the low intense $n$-type bulk contribution from deeper layers. A band diagram of the $p$–$n$ junction formed on the $n$-GaAs-surface by Ar$^+$ ion bombardment was reconstructed. The $p$–$n$ junction proved to be unexpectedly narrow compared to the extended tail of the implanted ion depth distribution.