Effect of silicon orientation and hydrogen anneal on tunneling from Si into SiO₂

Abstract

The issue of transverse momentum conservation in tunneling is examined by photon-assisted-tunneling measurements on metal-oxide-silicon structures. Results are compared for tunneling from silicon of 〈100〉, 〈110〉, and 〈111〉 orientations. The results for 〈100〉 and 〈110〉 are almost identical. For 〈111〉 it is concluded that the interface barrier energy is higher by about 0.5 eV than for 〈100〉 samples. This difference exists only for unannealed samples and is almost eliminated by the 400 °C standard forming gas (10% H 2, 90% N2) anneal. The barrier for the 〈111〉 interface has therefore a greater sensitivity to hydrogen than for the other two orientations. The experiments and their consistency with the usual (dark) Fowler-Nordheim tunneling from silicon into SiO2 show that transverse momentum (parallel to the interface) conservation is not observed.