Investigation of dislocations in Czochralski grown Si1-xGex single crystals

Abstract

Dislocations in p-type Si1-xGex single crystals (2-8 at% Ge) grown with the Czochralski technique are investigated by synchrotron white beam topography in transmission geometry. As the Ge concentration increases, the dislocation structure evolves from individual dislocations to slip bands and sub-grain boundaries, and the dislocation density increases from < 10(2) cm(-2) to 10(5)-10(6) cm(-2) at 8 at%. We discuss the effect of dislocations on the electrical characteristics such as resistivity rho(v), Hall hole mobility mu p, carrier lifetime tau(e) and I-V characteristics. Here tau(e) and I-V characteristics are measured from the diodes fabricated by bonding the p-Si1-xGex to n-Si wafers. I-V characteristics are not deteriorated in spite of a five times decrease in tau(e) with the Ge concentration.