Single Crystals of Exceptional Perfection and Uniformity by Zone Leveling

Abstract

The zone‐leveling process has been developed into a simple and effective tool, capable of growing large single crystals having high lattice perfection and containing an essentially uniform distribution of one or more desired impurities. Experimental work with germanium is discussed, and the possibility of broad application of the principles involved is indicated.

Antimony-doped germanium single crystals grown from the melt by the axial heat processing (AHP) technique

“…This effectively reduces the melt height above the interface, lowering the amount of convection in that region. Third, by separating the melt into two regions, AHP can impart the technique of zone leveling with a starting charge [20,[24][25][26][27][28][29] to eliminate the initial transient and spread the dopant more evenly along the length of the crystal. Fourth, the AHP method can make provisions to acquire temperature data from the growth domain with better accuracy by having thermocouples in the baffle near the s=l interface.…”

Single Crystal Silicon‐on‐Oxide by a Scanning CW Laser Induced Lateral Seeding Process

“…Therefore, if one can obtain a radiation source that has a trailing edge that is flat or concave to the direction of scan and a "top-hat" intensity profile, these problems can be overcome. This conclusion was also arrived at for traditional zone melting experiments (18). If this radiation source is available, the longitudinal mode of lateral seeding is preferred.…”

“…When the circular laser spot is scanned across the surface of the silicon, the motion of the laser spot induces an elliptically shaped isotherm in the thin silicon layer (17). It is known that thermal stress is induced by a nonplanar solid/melt interface because of the differential rate of contraction across the crystal (18). Furthermore, when a solid/ melt interface has a small radius of curvature, point defects can be trapped more easily in the solid, and there is also an increased chance of spurious nucleation (19).…”

Feasibility study of cadmium zinc telluride growth using a submerged heater in a vertical bridgman system

“…First, it provides increased control over the thermal environment, allowing manipulation of the melt/crystal interface shape to achieve a slightly convex interface, 10,14 which reduces thermal stresses and suppresses propagation of crystalline defects. Second, the heater divides the melt into two zones that communicate through a narrow annular channel, which allows use of the zone leveling technique 21,22,12 in which the two zones are loaded with different chemical compositions of starting materials. During growth, the zone that contains the crystal/melt interface is continuously fed with fresh material from the other zone, making it possible to maintain the desired composition at the crystal/melt interface throughout the growth process.…”