Improvement of nonlinearity and extension of wavelength region using tandem (PV plus PC) type HgCdTe detector (Dual-MCT) in FTIR spectrometer

A tandem (PV+PC) type HgCdTe detector (Dual-MCT) was fabricated to improve the nonlinear detector response and extend the wavelength region in Fourier transform infrared spectrometer. The backside-illuminated narrow band PV-M CT detector was arranged at the upper part of the hybrid device. A grid or a circular pattem electrode was formed on the active area to transmit the l onger wavelength light than cutoff. The appropriate reverse bias was applie d to the detector to obtain better linearity. The PC-MCT detector with a lo nger cutoff wavelength of middle band or wide band was arranged at the down part of the device to receive the transmitted light through the PV-MCT. Th e interferogram signals with better linearity from both detectors were comb ined after the phase matched preamplifier and Fourier transformed to a spec trum. The calibration curves evaluated with the absorption peaks at wavenum bers of 2025 and 972 cm(-1) of n-hexane showed that the Dual-MCT had excell ent linearity and wider wavelength coverage.