Room-temperature operation type-II GaSb/GaAs quantum-dot infrared light-emitting diodeShih‐Yen Lin, Chi‐Che Tseng, Wei-Hsun Lin et al.|Applied Physics Letters|2010 A GaSb/GaAs quantum-dot light-emitting diode (QD LED) with a single GaSb QD layer is investigated in this paper. The room-temperature photoluminescence peak blueshift with increasing excitation power densities suggests a type-II alignment of the GaSb/GaAs heterostructures. Significant electroluminescence (EL) is observed for the device under forward biases, which suggests that pronounced dipole transitions occur at the GaSb/GaAs interfaces. With increasing forward biases, the observed EL peak blueshift confirms that the origin of luminescence is from the type-II GaSb/GaAs QD structures. A model is established to explain the operation mechanisms of the type-II QD LED.
Influence of as on the Morphologies and Optical Characteristics of GaSb/GaAs Quantum DotsChi‐Che Tseng, Shu-Cheng Mai, Wei-Hsun Lin et al.|IEEE Journal of Quantum Electronics|2011 The influence of As atoms on the morphologies of GaSb quantum dots (QDs) is investigated. Without any special treatment, GaSb quantum rings (QRs) are observed in the embedded GaSb layer even when the uncapped layer reveals QD like morphologies. With intentional As supply after the uncapped GaSb QD deposition, a QD to QR transition is observed. The phenomenon suggests that insufficient Sb atoms on the GaSb QDs would lead to the QD to QR transition as in the case of embedded GaSb layers. With extended Sb soaking time following GaSb deposition, QD structures could be well maintained for the embedded GaSb layers. A light-emitting diode operated at room temperature is fabricated based on the GaSb/GaAs QD structure. Identical peak positions in photoluminescence and electroluminescence (EL) spectra of the device show that type-II GaSb QDs are responsible for the observed EL.
High-Temperature Operation GaSb/GaAs Quantum-Dot Infrared PhotodetectorsWei-Hsun Lin, Chi‐Che Tseng, Kuang-Ping Chao et al.|IEEE Photonics Technology Letters|2010 A ten-period GaSb/GaAs quantum-dot infrared photodetector (QDIP) is investigated in this letter. A broad detection window 2-5 μm with peak responses at ~ 3.7 μm is observed. Compared with the 4- to 8-μm detection window of a standard InAs/GaAs QDIP, the detection wavelengths of the GaSb/GaAs QDIP are shifted to the 2- to 5- μm range such that water absorption is avoided. The enhanced normal incident absorption of the GaSb QDIP is attributed to its smaller sizes compared with InAs QDs. Without additional high-bandgap barrier layers, the 200 K spectral response of the simple stacked GaSb/GaAs QDIP has already been observed, which has demonstrated the potential for practical applications of the GaSb/GaAs QDIPs.
Voltage-tunable two-color quantum-dot infrared photodetectorsShih‐Yen Lin, Wei-Hsun Lin, Chi‐Che Tseng et al.|Applied Physics Letters|2009 A two-terminal quantum-dot infrared photodetector with stacked five-period InAs/GaAs and InGaAs-capped InAs/GaAs quantum-dot (QD) structures is investigated. The device has exhibited distinct responses at mid-wavelength and long-wavelength infrared regions under positive and negative biases, respectively. The results suggest that the QD confinement states near the anode side are completely filled, such that selective responses at different wavelength ranges would be observed for the stacked structure under different voltage polarities. Also observed are the similar absorption ratios of the device under different incident light polarizations at the two response regions.
The transition mechanisms of type-II GaSb/GaAs quantum-dot infrared light-emitting diodesChi‐Che Tseng, Wei-Hsun Lin, Shung‐Yi Wu et al.|Journal of Crystal Growth|2010