We present here novel approaches of utilizing low energy range ions to form GaN layers on various substrates like GaAs (iso-structural and shared atom matching), silicon nitride (anti-surfactant) on Si(111) & Si(5 5 12) and SiC on Si (lattice parameter matching) substrates at room temperature. The experiments are performed in situ in an UHV chamber equipped with X-ray photoelectron spectroscopy as the probe.

1. GaN formation of GaAs(001):

A Ga rich surface produced by optimized Ar⁺ ion bombardment is followed by nitridation by using N₂⁺ ion of different energies of constant fluence. Systematic experiments show that 3 keV N₂⁺ ions and 7.2x10¹⁷ ions/cm² are the optimal energy and fluence, respectively, for the nitridation of GaAs (0 0 1) surface at room temperature.

2. Silicon nitride on Si surfaces:

The Si(111)-7x7 and the Si(5 5 12)-2x1 reconstructed surfaces have been converted into silicon nitride by using low energy N₂⁺ ions ranging from 250eV to 5keV. The optimal energy and flux for the N₂⁺ ions to form silicon nitride on low and high index Si surfaces have also been investigated.

 3. SiC layer on Si(111):

A few monolayers of graphitic carbon was adsorbed on Si(111) in UHV by ion beam sputtering which is subjected to 100eV to 1500eV Ar⁺ ion bombardment. The studies clearly demonstrate the Si-C bond formation after a threshold ion energy of 600eV, which correlates to the electron-hole pair production in Si. The core-level spectra manifest the interface reaction, while the valence-band spectra show the electronic-structure modifications.

We believe that these concepts of utilizing modified surfaces as templates for epitaxial GaN growth are technologically important, since it can be integrated easily with MBE growth.