Organometallic epitaxy of HgCdTe on CdTeSe substrates with high compositional uniformity

We report here on the growth of Hg_0.8Cd_0.2Te on lattice-matched substrates of CdTe_0.96Se_0.04 by organometallic vapor phase epitaxy. Results are compared with those for comparable layers grown on CdTe substrates. It is shown that the use of lattice-matched substrates results in active layers of improved structural quality, as evidenced by the results of double-crystal x-ray diffraction measurements. A compositional uniformity of better than ±0.005 (in the Cd composition) was obtained over 1 cm ×2 cm area substrates, corresponding to a standard deviation of 0.0024. The thickness uniformity was better than ±0.7 μm for 12-μm-thick layers. These layers were deposited by the direct alloy growth, without the interdiffusion of separate layers of HgTe and CdTe. Both n- and p-type layers have been grown by suitable modification to the growth process. Mobility values in excess of 6×10⁵ cm²/V s were obtained in n-type material (x=0.2), with an electron concentration below 1×10¹⁵ cm^-3. With p-type layers, mobility values of 400 cm²/V s were obtained with a hole concentration of 1×10¹⁷ cm^-3.