Low Dislocation-Density and Vacancy-Rich Glassy-Pinning Quasi GaAs Crystal by Liquid-Encapsulated Czochralski Growth

Abstract

ABSTRACTNot all threshold voltage (Vth) scattering of Si-implanted metal-semiconductor field- effect- transistors (MESFETs) on low dislocation density and semi-insulating (S.I.) liquid- glass encapsulation Czochralski (LEC) GaAs crystals grown at relatively high pull-speed were small. By comparison with the Lang x-ray topographs of the wafers, it was found that x-ray topograph contrast variations reflected on the films did not correspond with Vth variations of the wafers at all. Especially, in low dislocation density regions, which are in white regions on the films of the x-ray topographs, very large Vth turbulences were observed. We believe that dislocation-less in LEC GaAs crystals causes large Vth turbulences of Si-implanted MESFETs and that frozen cell-lattice-structure large turbulences by pinning centers associated with vacancies like glass cause large Vth turbulences.