Growth of Semiconductor Bulk Single Crystals

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Almost all electronic and optoelectronic devices need semiconducting materials of single crystalline structure. These materials are called single crystals, and are produced by a solidification process called crystal growth. Today, most bulk semiconductor single crystals are grown from the liquid phase by the growth processes known as the melt/solution techniques. These growth techniques have evolved from artisanship, relying very much on experience and intuition. Even today, this is the case in most techniques if not in all. The production of the same crystal twice is still a challenge. The applicant's research efforts have thus been focused on making these crystal growth techniques scientific so that the desired high quality crystals can be grown reproducibly. This is the main objective of the proposed research program. In the direction of achieving this main objective, the proposed research program will focus on: i) Growth of SixGe1-x (silicon germanium) single crystals from the germanium side by the Liquid Phase Diffusion (LPD) technique with higher silicon compositions (concentrations) up to 40%, ii) Growth of CdxZn1-xTe (CZT; cadmium zinc telluride) single crystals with uniform zinc (Zn) compositions by the Travelling Heater Method (THM) using tapered novel crucibles, and iii) Dissolution of silicon (Si) into germanium (Ge) melt at various temperature levels. Optimum growth conditions for uniform crystal composition, stable growth/dissolution interfaces, and most favorable mixing and impurity (dopant) transport in the liquid solution/melt will be determined by studying fluid flow, heat and mass transfer in the liquid phase (melt) and heat and mass transfer in the solid phases (grown crystal, feed)) occurring during these processes.