Characterizations of ZnTe bulks grown by temperature gradient solution growth

In this work, zinc telluride (ZnTe) bulk crystals have been grown for the first time by the temperature gradient solution growth (TGSG) technique. Hall effect and capacitance–voltage (C–V) measurements were used to determine the room temperature electrical properties, and low temperature photoluminescence (PL) measurements were used to analyze the optical properties. As grown undoped ZnTe shows p-type conductivity with the carrier concentration (1–2) × 1015 cm−3, mobility about 50 cm2/V s, resistivity about 80–90 Ω cm. Otherwise, heavily doped p-ZnTe can be achieved by phosphorus doping. The carrier concentration demonstrates a logarithmic increase with the doping amount. The Hall carrier concentration up to 8×1017 cm−3 (4.7×1018 cm−3 from C–V measurement), resistivity low to around 0.15 Ω cm was achieved with a doping amount of 4000 ppm ZnP2. Besides, the room temperature PL spectra exhibits a pure green luminescence of energy 2.259 eV (λ=549.5 nm). The peak intensifies with increasing ZnP2 doping amount and begins to saturate when the added amount is over 8000 ppm. The 9 K PL spectra also demonstrates that the excitonic zone is much more intense than for deep level band, indicating a good sample quality. It is plausible that using the TGSG technique can afford high-quality phosphorus-doped p-type ZnTe substrates for device applications.