Effects of uniaxial stress on the electronic state of the hydrogen–carbon complex in silicon

Abstract

We applied deep-level transient spectroscopy (DLTS) under uniaxial stress to study the structure and bonding character of a hydrogen–carbon complex. The application of 〈1 1 1〉 and 〈1 1 0〉 compressive stresses split the DLTS peak into two as intensity ratios of 1 : 3 and 2 : 2, respectively, which were the ratios of the low-temperature peak to the high-temperature peak. No splitting was observed under the 〈1 0 0〉 stress. These results indicate the trigonal symmetry of the complex and the antibonding character of its electronic state, and are consistent with the previously proposed atomic model of the complex, in which the hydrogen atom occupies the bond-centered site between silicon and carbon atoms. Furthermore, under the 〈1 1 1〉 stress, we observed that the energy of the electronic state corresponding to the low-temperature DLTS peak increased linearly with stress by 23±5 meV/GPa while that of the high-temperature peak only slightly decreased with stress by 6±5 meV/GPa. Under the 〈1 1 0〉 stress, the energy of the electronic state of the low-temperature peak had almost no stress dependency and that of the high-temperature peak decreased linearly with stress by 15±5 meV/GPa. Based on the above atomic model, we can consistently understand the opposite stress dependencies under 〈1 1 1〉 and 〈1 1 0〉 compressive stresses, considering the atomic displacement of the H–C complex under the stress.