Stress-induced level shift of a hydrogen-carbon complex in silicon

We have studied the stress-induced shift of a deep level at E_c - 0.15 eV due to a hydrogen-carbon complex in Si using deep-level transient spectroscopy (DLTS) under uniaxial compressive stress. Linear stress dependencies of the ionization energy of the above level were observed for five components of split DLTS peaks altogether for <111>, <110> and <100> stresses. By subtracting the stress shifts of conduction band minima from the stress dependencies of ionization energy, the net stress shifts of the energy level were obtained. Two piezospectroscopic parameters, A₁ and A₂, were determined as approximately 4 and -9.5 meV/GPa, respectively. Considering a molecular-orbital schematic suggested here and throughout, we conclude that the stress-induced level shifts and the splits pattern of DLTS peaks reflect the trigonal symmetry and antibonding character of the electronic state of the complex. These properties are completely consistent with the atomic configuration in which a hydrogen atom occupies the bond-centered site between Si and C atoms.