GROWTH OF (100)GAAS BY VERTICAL ZONE-MELTING

The vertical zone melt growth technique (VZM) was used to grow undoped, semi-insulating GaAs. Single crystals 34 mm in diameter were grown in the [100] direction. A molten zone length of 23 mm resulted in a solid-liquid interface which deviated only slightly from planarity to give a convex growing interface. With a vertical temperature gradient of 9-degrees-C cm-1 (measured in the furnace), the dislocation density was a uniform (2-5) x 10(3) cm-2 throughout the crystal. Hall measurements, carbon determinations and EL2 determinations all indicated that the GaAs had a relatively uniform impurity content in the first 80% of the crystal. VZM was also used to zone level Sn dopant to give an n-type carrier concentration varying by approximately 20% over 80% of the crystal length.