Influence of hydrogen on the optical absorption response of GaAs(Ti) films deposited by R.F. sputtering

In the present work we have investigated the optical absorption behavior of GaAs(Ti) films deposited by r.f sputtering technique under different H2 partial pressures. In previous work we have already demonstrated the feasibility to obtain GaAs films with high dose of Ti, which we refer to as GaAs(Ti). Any absorption peak, which could be related with the presence of an intermediate band, has been identified. The low Etauc parameter together with a broad Urbach tail of the films make us to suspect that the possible presence of an absorption peak could be hidden. The incorporation of H2 on sputtered GaAs films have demonstrated before a shift of the Etauc parameter to higher values and a reduction of the Urbach tail.