Growth and characterization of Br-doped ZnSe single crystals grown by a vertical sublimation method

Bromine doping of ZnSe single crystals grown by using a vertical sublimatio n method was studied. ZnBr2 was used as a dopant at concentrations of 0.003 to 0.1 mg/cm(3) in the ampoules. When the Br-doping was 0.01 mg/cm(3) or l ess, the average growth rate of the crystals was about 34 mg/h cm(2); the s ame as that without doping. When the Br-doping exceeded 0.01 mg/cm(3), the average growth rate decreased with increasing dopant concentration. The und oped ZnSe crystals were yellow, whereas the Br-doped ZnSe crystals were ora nge. The high quality of the grown crystals was confirmed by X-ray diffract ion (XRD), which showed that the full width at half maximum (FWHM) of the r ocking curve ranged from 6.7 to 8.9 arcs. Bromine concentration of the grow n crystals ranged from 4 x 10(17) to 1.5 x 10(19) cm(-3) (measured by secon dary ion mass spectrometry, SIMS), depending on the dopant concentration. A ll of the as-grown crystals showed high resistivity. After growth, all of t he grown crystals were annealed in a Zn atmosphere at 1100 degreesC for 100 h to activate the bromine as an n-type donor. When the dopant concentratio n was increased, the carrier concentration of Br-doped ZnSe increased from 1.4 to 4.1 x 10(17) cm(-3) and the mobility decreased from 366 to 146 cm(2) /Vs (determined by Hall effect measurements). Our results show that high qu ality, low resistivity ZnSe single crystals can be grown by this vertical s ublimation method. (C) 2001 Elsevier Science B.V. All rights reserved.