Spatially resolved and two-dimensional mapping modulated infrared photoluminescence spectroscopy with functional...

The pixel-scale nonuniformity of the photoelectric response may be due either to the in-plane electronic inhomogeneity of the narrow-gap semiconductor or to the craft fluctuation during the fabrication process, which limits the imaging performance of the infrared focal plane array (FPA) photodetector. Accordingly, a nondestructive technique is most desirable for examining the spatial uniformity of the optoelectronic properties of the narrow-gap semiconductor to identify the origin of the FPA response nonuniformity. This article introduces a spatially resolved and two-dimensional mapping infrared photoluminescence (PL) technique, especially suitable for characterizing FPA narrow-gap semiconductors, based on the modulated PL method with a step-scan Fourier transform infrared spectrometer. The experimental configuration is described, and typical applications are presented as examples to a 960 × 640 μm² area of an InAsSbP-on-InAs layer in the medium-wave infrared range and a 960 × 960 μm² area of a HgTe/HgCdTe superlattice (SL) in the long-wave infrared range. The results indicate that, within a measurement duration of about 30 s/spectrum, a sufficiently high signal-to-noise ratio (SNR) of over 50 is achieved with a spectral resolution of 16 cm^-1 for the InAsSbP-on-InAs layer and a SNR over 30 is achieved with a spectral resolution of 12 cm^-1 for the HgTe/HgCdTe SL, which warrants reliable identification of the subtle differences among the spatially resolved and two-dimensional mapping PL spectra. The imaging of the in-plane distribution of PL energy, intensity, and linewidth is realized quantitatively. The results indicate the feasibility and functionality of the spatially resolved and two-dimensional mapping PL spectroscopy for the narrow-gap semiconductors in a wide infrared range.