Deep levels of chromium-hydrogen complexes in silicon

Deep levels related to chromium in n-type silicon have been investigated using deep level transient spectroscopy (DLTS) and concentration profile measurements. The DLTS measurement reveals four electron traps of E _C-0.22, E_C-0.28, E_C-0.45, and E _C-0.54 eV in chromium-doped samples. The trap of E_C-0.22 eV is a donor due to interstitial chromium. The other three traps are observed near the surface region of samples etched with an acid mixture containing HF and HNO₃ and annihilate after annealing at 175°C for 30 min. The origin of these traps has been studied by isochronal annealing and various chemical treatments. It is demonstrated that the three electron traps are due to complexes of interstitial chromium and hydrogen.