Charge transfer characteristics of the long wavelength semiconductor laser structures, containing quantum dot layers (QDs), were investigated by means of temperature dependent current-voltage and electroluminescence measurements over InAs/InP, and InAs/GaAs based p-i-n structures. In InAs/InP elongated QDs (QDashes) structure, injected carriers were tunneled from the quantum well into QDashes through a thin barrier and subsequently recombined within QDashes. Meanwhile, for InAs/GaAs structure, tunneling kind transport was exhibited in both forward and reverse bias voltage directions. The onset of light took place when the forward bias exceeded 1.3 V (3 V) for InAs/InP (InAs/GaAs) p-i-n structure through electroluminescence measurements. The peak value of emitted laser light for InAs/InP QDashes and InAs/GaAs QDs occurred in 1.55 µm and 1.3 µm, respectively.
Investigation of structural quality (by x-ray diffraction) and analysis of defects and interfaces in epitaxial layers (by transmission electron microscopy (TEM)) have been performed on InGaN/ GaN multiple quantum wells (MQWs) LED structure. Using energy dispersive x-ray analysis attached to the TEM system, 30% indium content in the InGaN well was measured. For electrooptic analysis, 30% in content InGaN/GaN MQWs LED in the p-i-n structure was analyzed through admittance spectroscopy and photo/electroluminescence (PL/EL) measurements. Electrical properties of the present LED structure were outlined first using AC admittance and DC current-voltage analyses. Trap level(s) in quantum wells (sub-bandgap) and the active layer of the p-i-n structure were defined by PL/EL measurement. Consumption of carriers through radiative recombination and trap filling/emptying processes (via these levels) competed with each others. This resulted in a non-equilibrium situation and originated from the inductive current. The analytically derived expression for the admittance in bipolar carrier injection was applied. It accounted for very good fits to the experimentally measured negative capacitance. The goodness of fits verified that recombination occurred faster than the trap filling/emptying process, causing the non-equilibrium situation.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.