ZnGeP2 grown by the liquid encapsulated Czochralski method

Abstract

The growth of ZnGeP2 by the liquid encapsulated Czochralski method is reported for the first time herein. Large boules of ZnGeP2, with diameters up to 40 mm and weights up to 400 gm were grown by Czochralski pulling from B2O3 encapsulated melts under high pressure (20 atm Ar) using axial gradients ≤120 °C/cm. Boules pulled at ≤4 mm/h exhibited large (50×20×15 mm3) monocrystalline grains of α-phase ZnGeP2 with room temperature electrical properties of p-type conduction, carrier concentrations ranging from 1012 to 1016 cm−3, and mobilities of 20 cm2/V s or less. Optical samples exhibited broad IR transmission (0.7 to 12.5 μm), second harmonic generation at 4.7 μm with 7.2% conversion efficiency, a broad subband gap photoluminescence signature, and near band-edge absorption similar to that observed in Bridgman-grown ZnGeP2.

Growth and thermal annealing effect on infrared transmittance of ZnGeP2 single crystal

“…It is widely used for OPO due to its unique set of optical properties, including wide potential transmission range (0.7-12 mm), large nonlinear coefficient (d 36 ¼75 pm/V) and high thermal conductivity (0.35 W cm À 1 K À 1 ) [1]. The main method to prepare ZnGeP 2 single crystal is melt directional solidification such as vertical Bridgman (VB) method [2], vertical gradient freezing (VGF) method [3] and horizontal gradient freezing (HGF) method [4].…”

Growth and annealing characterization of ZnGeP2 crystal

“…Asgrown ZGP using the method of horizontal gradient freezing (HGF) [9][10][11] was analyzed on its properties and defects. ZGP grown by the liquid encapsulated Czochralski method (LEC, [12]) was mainly illustrated electrical behavior. In addition, ZGP optical samples obtained by LEC method presented broad IR transmission (0.7-12.5 mm) and SHG at 4.3 mm with a 7.2% conversion efficiency [12].…”

Growth and characterization of ZnGeP2 single crystals by the modified Bridgman method

“…In recent years, considerable effort was focused on the growth of high-quality single crystals of this material. In order to overcome some problems in ZGP crystals growth, the single crystals are grown by various methods such as the vertical Bridgman (VB) [9], vertical gradient freezing (VGF) [10], horizontal gradient freezing (HGF) [11], liquid encapsulated Czochralski (LEC) [12], highpressure vapor transport (HPVT) [13] methods, etc. For the present, the most conventional techniques for the growth of ZGP single crystals remain the VB and HGF methods [14][15][16].…”