نتایج جستجو برای: Band-edge, Engineering energy levels, QD laser, Quantum dot size, Strain PACS numbers: 73.63.Kv
تعداد نتایج: 3126311 فیلتر نتایج به سال:
In this paper, we have studied the strain, band-edge, and energy levels of cubic InGaAs quantum dots (QDs) surrounded by GaAs. It is shown that overall strain value is larger in InGaAs-GaAs interfaces, as well as in smaller QDs. Also, it is proved that conduction and valence band-edges and electron-hole levels are size dependent; larger QD sizes appeared to result in the lower recombination...
In this paper, modulation bandwidth characteristics of InGaAs/GaAs quantum dot (QD) laser were theoretically investigated. Simulation was done by using the fourth order Runge-Kutta method. Effect of carrier relaxation life time, temperature and current density on characteristics of tunneling injection QD laser (TIL) and conventional QD laser (CL) were analyzed. Results showed that tunneling inj...
We present a theory of electronic properties of HgTe quantum dot and propose a strain sensor based on a strain-driven transition from a HgTe quantum dot with inverted bandstructure and robust topologically protected quantum edge states to a normal state without edge states in the energy gap. The presence or absence of edge states leads to large on/off ratio of conductivity across the quantum do...
As thermalisation loss is the dominant loss process in the quantum dot intermediate band solar cells (QD-IBSCs), it has been investigated and calculated for a QD-IBSC, where IB is created by embedding a stack of InAs(1-x) Nx QDs with a square pyramid shape in the intrinsic layer of the AlPySb(1-y) p-i-n structure. IB, which is an optically coupled but electrically isolated mini-band, divides th...
Different approaches to the design of a genuinely temperature-insensitive quantum dot (QD) laser are proposed. Suppression of the parasitic recombination outside the QDs, which is the dominant source of the temperature dependence of the threshold current in the conventional design of a QD laser, is accomplished either by tunneling injection of carriers into the QDs or by band-gap engineering. E...
Data are presented showing that, besides the improvement in carrier collection, it is advantageous to locate strain-matching auxiliary InGaAs layers @quantum wells ~QWs!# within tunneling distance of a single-quantum-dot ~QD! layer of an AlGaAs–GaAs–InGaAs–InAs QD heterostructure laser to realize also smaller size QDs of greater density and uniformity. The QD density is changed from 2310/cm for...
We study the electronic transport through a quantum wire (QW) with a strong side coupled quantum dot (QD). We obtain a linear conductance with lateral peaks when the gate voltage, is located near the edge of the conduction band. The calculated density of states shows, that these peaks are associated with renormalized localized levels out side of the conduction band. These results are compatible...
An extraordinary temperature dependence of the resonant Andreev reflection via discrete energy level in a normal-metal / quantum-dot / superconductor (N-QD-S) system is predicted theoretically by using Green function technique. The width of zero bias conductance peak in N-QD-S is about √ ΓL + Γ 2 R and does not exhibit thermal broadening, where ΓL and ΓR are the coupling strength between QD and...
The modulation response, relative intensity noise (RIN) and frequency noise (FN) characteristics of quantum dot (QD) lasers are investigated theoretically in the presence of an external optical beam. Using small signal analysis of the rate equations for carriers and photons, it is demonstrated that by injecting excess carriers into the QDs excited state through optical pumping, the modulation r...
In this paper, we present the generation of high peak-power picosecond optical pulses in the 1.26 μm spectral band from a repetition-rate-tunable quantum-dot external-cavity passively mode-locked laser (QD-ECMLL), amplified by a tapered quantum-dot semiconductor optical amplifier (QD-SOA). The laser emission wavelength was controlled through a chirped volume Bragg grating which was used as an e...
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