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Interband cascade light-emitting diodes (ICLEDs) offer attractive advantages for infrared applications, which would greatly expand if high-quality growth on silicon substrates could be achieved. This work describes the formation of threading dislocations in ICLEDs grown monolithically on GaSb-on-Silicon wafers. The epitaxial growth is done in two stages: the GaSb-on-Silicon buffer is grown first, followed by the ICLED growth. The buffer growth involves the nucleation of a 10-nm-thick AlSb buffer layer on the silicon surface, followed by the GaSb growth. The AlSb nucleation layer promotes the formation of 90° and 60° interfacial misfit dislocations, resulting in a highly planar morphology for subsequent GaSb growth that is almost 100% relaxed. The resulting GaSb buffer for growth of the ICLED has a threading dislocation density of ∼107/cm2 after ∼3 μm of growth. The fabricated LEDs showed variations in device performance, with some devices demonstrating comparable light–current–voltage curves to those for devices grown on GaSb substrates, while other devices showed somewhat reduced relative performance. Cross-sectional transmission electron microscopy observations of the inferior diodes indicated that the multiplication of threading dislocations in the active region had most likely caused the increased leakage current and lower output power. Enhanced defect filter layers on the GaSb/Si substrates should provide more consistent diode performance and a viable future growth approach for antimonide-based ICLEDs and other infrared devices. [ABSTRACT FROM AUTHOR]

We present the growth of highly relaxed In0.53Ga0.47Sb buffers on In0.53Ga0.47As/InP by inducing a periodic array of interfacial misfit dislocation arrays at the In0.53Ga0.47Sb/ In0.53Ga0.47As interface. The periodic 90° misfit dislocation array is realized through As for Sb anion exchange while keeping the group III sublattice the same. Transmission electron microscopy (TEM) results show the presence of misfit dislocations with a periodicity of 6.16 nm, which corresponds to 14 In0.53Ga0.47Sb lattice sites or 15 In0.53Ga0.47As lattice sites. The In0.53Ga0.47Sb epilayer, however, is affected by phase segregation as evidenced by both TEM and Nomarski optical phase microscopy. The x ray based reciprocal space mapping indicates relaxation to be 99.5% for the In0.53Ga0.47Sb epilayer. [ABSTRACT FROM AUTHOR]

We report a simple method to improve the p-type doping efficiency and eliminate the diode leakage current in selective-area-grown GaN-based core-shell nanostructure LEDs by growing an n-type AlGaN layer underneath the InGaN/GaN active region. A significant reduction in reverse-leakage current density is correlated with longer AlGaN layer growth time and higher flow rate of the aluminum precursor. A comparison of the SIMS profiles with and without the underlayer indicates a high concentration of donor-type impurities (e.g., silicon and oxygen) in the p-GaN layer in the structure with no AlGaN underlayer. Conversely, LEDs with an AlGaN underlayer exhibit enhanced magnesium incorporation and much lower silicon and oxygen impurity concentrations within the p-GaN layer. The reverse current density was also reduced by the addition of a p-type AlGaN electron blocking layer above the active region. [ABSTRACT FROM AUTHOR]

Focused ion beam interaction profiles and nanomachining mechanisms are very different for membrane and bulk samples. In this work, a detailed empirical study was carried out to understand these differences by observing the progression of helium ion milling in silicon single crystalline membranes and bulk samples using cross-sectional transmission electron microscopy. The components of backward sputter yield and forward sputter yield unique to the membrane samples were observed, analyzed, and contrasted with the bulk sample sputter yield. [ABSTRACT FROM AUTHOR]