Second harmonic generation by reflection from vicinal surfaces of epitaxial layers of cadmium mercury telluride

Reflection second harmonic generation is employed to examine the surfaces o f epitaxial layers of CdxHg1-xTe (CMT) grown on vicinal GaAs (100) substrat es. Different vicinal tilts, with respect to the GaAs substrates, are obser ved in the epitaxial CMT layers. We also report here on the measurement of the second-order nonlinear coefficient (d(36)) Of CMT. Because CMT is stron gly absorbing at the 1.06 mum wavelength, this measurement was performed by comparing the second harmonic intensity reflected from the CMT surface to that measured for a quartz sample in transmission. Directly comparable expr essions for the reflected and transmitted second harmonic intensities are d erived from which a value of d(36) = 365 +/- 15 pm V-1 is obtained. This va lue is much larger than those reported for similar zinc-blende-type materia ls and is attributed to an electronic resonance enhancement.