Nucleation Control in Physical Vapor Transport Growth of AlN Single Crystals on Polycrystal Tungsten Substrates

• Main Authors: Honglei WU, Zuoyan QIN, Xueyong TIAN, Zhenhua SUN, Baikui LI, Ruisheng ZHENG, Ke WANG
• Format: Article
• Language: English
• Published: Kaunas University of Technology 2019-12-01
• Series: Medžiagotyra
• Subjects: growth from vapor; single-crystal growth; nitrides; x-ray diffraction
• Online Access: http://matsc.ktu.lt/index.php/MatSc/article/view/21575

The improved resistively-heated furnace with two heaters established a vertical thermal gradient to control nucleation during AlN single crystals Physical Vapor Transport (PVT) growth on polycrystal tungsten substrates. During the high temperature (> 1850 °C) heating process, the reverse temperature field (i.e., the temperature difference between the sublimation zone and the crystalline zone ΔT < 0) was obtained to reduce the number of nuclei on the tungsten substrate. During growth, the proper positive values of ΔT T were chosen to content the supersaturation values (0.25 < S < 0.3). The reverse temperature condition during high temperature (> 1850 °C) cooling was fulfilled to avoid recrystallization on grown AlN crystal. AlN single crystals made through the method were characterized by X-ray diffractions (XRD) and Raman spectroscopy.