Infrared-modulated photoluminescence spectroscopy: From wide-band coverage to micro-area and high-throughput scanning imaging

Photoluminescence (PL) spectroscopy has been widely used in the ultraviolet-near-infrared spectral range for over seventy years since its early reporting in the 1950’s, because it not only reveals the electronic structure information about such as band gap and impurity energy levels of semiconductor materials, but also serves as an efficient tool for analyzing interfacial structures, carrier lifetime, and quantum efficiency. However, in the infrared band beyond about 4 μm, the study of PL spectrum has been limited for decades due to strong thermal background interference, weak PL signals and low detection capability. In this review, a traditional PL method is introduced based on a Fourier transform infrared (FTIR) spectrometer, and a continuous-scan FTIR spectrometer-based double-modulation PL (csFTIR-DMPL) method is briefly described which was proposed in 1989 for breaking through the dilemma of the infrared band, and developed continuously in the later more than 20 years, with its limitations emphasized. Then, a step-scan FTIR spectrometer-based infrared modulated PL (ssFTIR-MPL) method reported in 2006 is analyzed with highlights on its advantages of anti-interference, sensitivity and signal-to-noise ratio. The effectiveness demonstration and application progress of this method in many research groups around the world are listed. Further developments in recent years are then summarized of wide-band, high-throughput scanning imaging and spatial micro-resolution infrared modulated PL spectroscopic experimental systems, and the technological progresses are demonstrated of infrared-modulated PL spectroscopy from 0.56–20 μm visible-far-infrared broadband coverage to >1000 high-throughput spectra imaging and ≤2–3 μm spatial micro-resolution. Typical achievements of collaborative research are enumerated in the visible-far-infrared semiconductor materials of dilute nitrogen/dilute bismuth quantum wells, HgCdTe epitaxial films, and InAs/GaSb superlattices. The results presented demonstrate the advancement of infrared modulated PL spectroscopy and the effectiveness of the experimental systems, and foresee further application and development in the future.