MIOMD - XVI 2023 Session MIOMD-TuA1: ICLs and LEDs

Since the first demonstration of continuous wave operation [1] Interband Cascade Lasers (ICLs) have shown tremendous improvement in their performance. Not only cw operation up to a temperature of more than 100°C has been shown [2] but also the capability of the interband cascade concept to operate to wavelengths beyond 13µm [3]. Recently we demonstrated another design improvement which focusses on the mitigation of intervalence band absorption [4]. This in turn led to a significant improvement of laser performance in the wavelength region around 6 µm [5]. A spectrum and LIV characteristics of an epi down mounted laser are shown in Figure 1. Furthermore, the latest results on resonant cavity ICLEDs and long wavelength ICLEDs with emission um to 10.2µm will be shown.

Interband cascade light emitting diodes (ICLEDs) grown on GaSb substrates have emerged as an effective continuous wave (CW) room temperature emitter technology in the 3 – 5 µm wavelength range [1,2]. The integration of ICLEDs directly on a silicon substrate can lead to significant benefits in manufacturability for applications including chemical sensing and IR scene projectors (IRSPs).

This presentation will discuss the growth at NRL of high performance ICLEDs on GaSb/Si buffers that were grown at UNM. The growths on GaSb vs. GaSb/Si are compared for crystallographic quality using cross section transmission electron microscopy (XTEM) and X-Ray reciprocal space maps (RSM). XTEM images show the presence of threading dislocations in the GaSb buffer grown on Si, with a higher density near the silicon substrate and reduced closer to the ICLED. We measure a range from 5 x 10⁷ to 2 x 10⁸ cm² in different samples. Individual threading dislocations in the GaSb buffer can reach the ICLED and multiply once they reach the active stages (figure 1). Another artifact of growth on silicon is an undulation in the ICLED layers. Our presentation will provide a detailed mechanism for both of these observations, and we will compare the results to those for an ICLED grown lattice-matched to a GaSb substrate (figure 2). We will also discuss possible strategies for improving the epitaxial quality and device performance.