Effective cavity length method is introduced to vertical cavity surface emitting laser for characterizing some properties, including reflectivity, FWHM, mode wavelength and thresh-old gain. Some experiment results are demonstrated, showing the agreement of theoretical analysis with experiment. 相似文献
We report on the optical properties of monolithic GaN‐based airpost pillar microcavities (MCs) with embedded InGaN quantum wells or quantum dots (QDs), respectively. The presented MCs are designed by use of different kinds of distributed Bragg reflectors consisting of either AlGaN/GaN, AlInN/GaN, or superlattices of AlN/InGaN and GaN. A quality factor of up to Q = 260 has been achieved. Airpost pillar MCs, providing a three‐dimensional optical confinement, are realized by focused ion beam etching starting from an all‐epitaxially grown vertical‐cavity surface‐emitting laser structure. Pillar diameters below 1 µm are well controllable. The sidewalls are smooth and show a damaged surface layer of a thickness less than 2 nm only. Microphotoluminescence (µ‐PL) measurements reveal the longitudinal and transversal mode spectra of the cavities in good agreement with theoretical calculations based on a vectorial transfer‐matrix method. Furthermore, the spectra of the QD based samples reveal distinct spectrally sharp emission lines around 2.73 eV which can be attributed to the emission of single‐InGaN QDs and traced up to 120 K.
The effect of bismuth on the optical properties of InGaAsBi/GaAs quantum well structures is investigated using the temperature-dependent photoluminescence from 12 K to 450 K.The incorporation of bismuth in the InGaAsBi quantum well is confirmed and found to result in a red shift of photoluminescence wavelength of 27.3 meV at 300 K.The photoluminescence intensity is significantly enhanced by about 50 times at 12 K with respect to that of the InGaAs quantum well due to the surfactant effect of bismuth.The temperature-dependent integrated photoluminescence intensities of the two samples reveal different behaviors related to various non-radiative recombination processes.The incorporation of bismuth also induces alloy non-uniformity in the quantum well,leading to an increased photoluminescence linewidth. 相似文献
Abstract Here we report what we believe to be the first observation of the pressure dependence of the light hole behavior in a modulation doped In0.18Ga0.82As/GaAs single strained quantum well grown by MBE. Transport measurements have been undertaken as a function of temperature (4–300K) and hydrostatic pressure (4–8kbar). Hole mobilities of ～17000 cm2/Vs have been obtained for sheet carrier densities of ～3.3×1011 cm?2. At low temperatures (<100K) persistent photogenerated holes have been observed. The hole mobility is found to decrease with increasing pressure at a rate intermediate between that typically observed for holes and electrons in bulk III-V semiconductors. 相似文献
Spontaneous emission characteristics of hybrid InxGa1 − xN/Cd0.05Zn0.95O quantum well (QW) structures were theoretically investigated by using multi‐band effective mass theory. The transition wavelength of the InGaN/CdZnO QW structure is shown to be changed from 415 to 580 nm when the In content x is varied from 0.1 to 0.3. The conventional InGaN/GaN QW structure shows that its peak intensity linearly decreases with increasing peak wavelength. On the other hand, the InGaN/CdZnO QW structure shows that the spontaneous emission coefficient reaches a maximum at around the peak wavelength of 0.484 µm, which corresponds to x = 0.2. This can be explained by the fact that, in a range of the short peak wavelengths, the InGaN/CdZnO QW structure has a very shallow potential well. In a range of the longer peak wavelengths above 0.47 µm, the InGaN/CdZnO QW structure is expected to have a larger spontaneous emission peak than the InGaN/GaN QW structure. This can be explained by the fact that the former has a reduced internal field compared to the latter. 相似文献
We have determined the band offsets at the highly strained InAs/GaAs heterointerface by photoluminescence excitation (PLE) measurements of the symmetric and antisymmetric states in two coupled ultrathin InAs layers embedded in a GaAs matrix. The conduction band offset ΔEccould be separated from the valence band offsets, since in a 32 monolayer (ML) barrier sample, the splitting between the heavy-hole exciton transitions is solely determined by ΔEc. Knowing ΔEc, the heavy-hole (hh) and light-hole (lh) band offsets ΔEhhand ΔElhcould subsequently be determined from the coupling-induced shift and splitting in samples with a 16, 8 and 4 ML barrier. We find a conduction band offset of 535 meV, a conduction band offset ratio ofQc= 0.58 and a strain induced splitting between the hh and lh subbands of 160 meV. 相似文献
Achieving low-threshold optical gain for solution-processed materials is crucial for their real-life applications and deployment as gain media. However, the realization of low gain threshold in the blue region has shown to be technically an extremely challenging task using colloidal nanocrystals as a result of fast nonradiative Auger rates in smaller nanocrystals. Here, ultralow-threshold blue amplified spontaneous emission (ASE) (≈2.7 µJ cm−2) accompanied with a large net modal gain coefficient of 360 cm−1 in the blue enabled by blue-emitting (≈455–465 nm) colloidal quantum rings (QRs) of inverted type-I CdS/CdSe core/crown nanoplatelets (NPLs) is proposed and demonstrated. The synthesized QRs with controlled crown size outperform the best reported ASE thresholds and net modal gain coefficients from the solution-processed materials by ≈2.5- and ≈4-fold, respectively, in the similar blue spectral window. Utilizing this QR architecture, it is also shown that the ASE peak can be spectrally tuned by controlling the lateral size of the crown and hence quantum confinement in the lateral direction. These outstanding results support the prospects of these solution-processed QRs made of 2D hetero-NPLs in the challenging blue region as colloidal gain. 相似文献
