Growth of cadmium zinc telluride by liquid phase electroepitaxy

Abstract

This study was undertaken to examine the feasibility of growing CdZnTe by liquid phase electroepitaxy. Based on our successful LPEE system of GaInAs, a new crucible to grow CdZnTe was developed. The development presented numerous difficulties. The physical properties of CdZnTe make this material very difficult to grow. All components of the system were investigated. Electromigration of the solute across the solution carries species towards the growth interface. In liquid Cd-Zn-Te, the CdTe and ZnTe species remain associated, contrary to the GaInAs system. Experiments showed that LPEE growth of CdZnTe is possible and the electromigration mechanism functions well in the CdZnTe solution. Despite this, other problems remained with the new LPEE system. The preparation of the solution proved difficult without pressurizing the LPEE crucible. Control of the reaction required the use of pre-compounded CdTe and ZnTe. Proper control of the solution saturation is imperative to ensure minimal dissolution of the seed prior to growth initiation and a reasonable growth rate during growth. The solution remained an issue during the duration of growth due to the high vapor pressures of the constituents. Tellurium evaporation during growth could lower solution volume until electrical contact across the solution is broken. Careful preparation of appropriate solution volume was imperative for successful growth. In LPEE, a uniform electric current passage across the growth interface is necessary for uniform and stable growth interface. This requires the design of a uniform contact zone between the bottom graphite electrode and the seed crystal. The contact zone issue was not adequately resolved in this study. However, a number of successful growth runs were achieved despite the electrical contact problems. Results show that the LPEE of growth CdZnTe is feasible.

Control of growth uniformity of III–V bulk crystals grown by contactless liquid phase electroepitaxy

“…Moreover, they need to be supplemented by As diffusivity in liquid Ga, denoted by D, determining the flux of arsenic related to its concentration gradient in the liquid. Finally, electromigration of As species dragged by the motion of electrons in the liquid metal is described by effective As mobility m [5,9].…”

“…Unfortunately, thicknesses only upto 3 mm were obtained , so LPEE still belongs to laboratory growth domain. On the other hand, LPEE offers crystals that are distinguished by defect concentration and compositional uniformity not attainable by other solution or melt growth techniques [5,9].…”

Unlimited Growth of III–V Bulk Crystals by Liquid-Phase Electroepitaxy

“…In addition, electromigration of As ions dragged by the motion of electrons in the liquid metal is described by the effective ion mobility μ. 5,9 The values of all these parameters are listed in Table 1.…”

“…In addition, LPEE-grown crystals are characterized by defect concentration and compositional uniformity that is not attainable by other solution or melt growth techniques. 5,9 The hope for a new route was dashed by the Joule heat release in the solid bulk which slows down and ultimately stops growth. Therefore, LPEE still belongs to the laboratory growth domain as the produced ingots are small in comparison to commercially available IIIÀV crystals, grown by other techniques.…”

“…and thicknesses up to 3 mm. In addition, LPEE-grown crystals are characterized by defect concentration and compositional uniformity that is not attainable by other solution or melt growth techniques. , …”