Crystal growth and characterization of Cd_0.8Mn_0.2Te using Vertical Bridgman method

By Vertical Bridgman method, several Cd_0.8Mn_0.2Te (CdMnTe) ingots were grown. The structure and crystallinity of the ingots were evaluated by X-ray powder diffraction and double-crystal rocking curve measurement and etch pits density (EPD) measurement. The results showed a pure cubic zinc blende structure throughout the ingots with the full width at half maximum (FWHM) of 40-70 arcsec and EPD of (6-8) × 10⁴ cm^-2, indicating a high crystalline perfection. The Mn concentration distribution along the axial and radial direction of the ingots was measured by inductively coupled plasma atomic emission spectrometer (ICP-AES). The segregation coefficient k_eff for Mn along the axis of the ingots is determined to be 0.95, and the radial variation of Mn concentration is within 0.002. Current-voltage (I-V) measurement reveals that sputtered Au film can form good ohmic contact to CdMnTe wafer and all the wafers of the as-grown crystals have the resistivity within (1-4) × 10⁶ Ω cm. IR transmission measurement in the wave number region from 4000 to 1000 cm^-1 exhibits that the IR transmittance of CdMnTe wafers is 50-55%, which is close to the theoretical value.