Blue lasing at room temperature in an optically pumped lattice-matched AlInN/GaN VCSEL structure

Abstract

Laser action with low threshold average pump power density ( $ 50 W Á cm À2 ) at room temperature is reported for a crack-free planar vertical cavity surface emitting laser (VCSEL) structure based on a bottom lattice-matched AlInN=GaN distributed Bragg reflector (DBR) and a top dielectric DBR. The cavity region, formed by n-and p-type GaN layers surrounding only three InGaN=GaN quantum wells, corresponds to a typical active region suitable for an electrically driven VCSEL. In addition to low threshold, a spontaneous emission coupling factor b $ 2 Â 10 À3 is derived for this ready-to-be-processed laser structure.In recent years III-nitride semiconductor optoelectronic devices have undergone tremendous development with the progressive commercialisation of blue-violet and white light emitting diodes and that of blueviolet edge-emitting laser diodes (LDs) [1]. However, demonstration of an electrically pumped compact laser source such as vertical cavity surface emitting lasers (VCSELs) has not been reported. Recent advances in the growth of high quality epitaxially-grown nitridebased distributed Bragg reflectors (DBRs) have allowed for significant improvement of the quality factor Q( ¼ l=Dl) of planar microcavity (MC) structures [2] with the recent demonstration of Q values up to 2800 in a crack-free empty lattice-matched (LM) AlInN=GaN-based MC [3]. Lasing in planar nitride VCSEL structures under optical pumping has been reported by several groups [2, 4-7] but usually the active region consists of more than ten quantum wells (QWs) to increase modal gain and overcome optical losses. Actually, in electrically pumped LDs there is usually a trade-off between modal gain and threshold current which leads to an optimum number of wells between three and five. So far there is, to the best of our knowledge, only one report of room-temperature lasing action in an optically pumped nitride VCSEL structure containing less than ten QWs, namely in a 4l AlGaN cavity with three InGaN QWs sandwiched between two high reflectivity (R $ 99%) dielectric (SiO 2 =ZrO 2 ) DBRs [8]. However, the realisation of the latter structure requires lengthy and advanced processing steps which are not compatible with an electrical injection scheme.In this Letter we report on the blue-violet lasing action, at $ 422 nm, under optical pumping with a low average threshold power density of 50 W Á cm À2 in a crack-free planar hybrid 5l=2 GaN MC containing three InGaN QWs with a bottom LM AlInN=GaN DBR and a top dielectric (SiO 2 =Si 3 N 4 ) DBR. The cavity region has both n-and p-type regions as well as an AlGaN electron blocking layer on the p side making such a planar design in all points identical to that of a real structure ready to be processed to fabricate mesas and deposit electrical contacts. A spontaneous emission coupling factor b $ 2 Â 10 À3 is derived from the input-output characteristics for this VCSEL structure.The nitride vertical cavity structure was grown by metal organic vapour phase epitaxy (MOVPE) on a 2-inch c-plane sapphire substrate in a...

Tailoring the strong coupling regime in III‐nitride based microcavities for room temperature polariton laser applications

“…To complete our analysis, we also studied the evolution of the RT lasing threshold power density P thr measured on an InGaN/GaN MQW vertical cavity surface emitting laser (VCSEL) similar to that of Ref. [33] using the abovementioned nonresonant excitation scheme as a function of δ (Fig. 6(a)).…”

Temperature Dependent Capacitance–Voltage Analysis of Unintentionally Doped and Si Doped Al0.82In0.18N Grown on GaN

“…2) These two features make Al x In 1Àx N an ideal material for a high quality Al x In 1Àx N/GaN distributed Bragg reflector for visible and near ultraviolet optoelectronics. 3,4) The spontaneous large polarization difference with respect to GaN also gives rise to the high sheet charge density two dimensional electron gas (2DEG) at the Al x In 1Àx N/GaN interface without strain-induced polarization. The absence of the latticemismatch related stress improves the structural stability and thus the reliability of the electronic devices.…”

Development of GaN-Based Vertical-Cavity Surface-Emitting Lasers

“…As far as optically pumped GaN-based VCSELs are concerned, there are only few experimental results in recent years [22]- [25]. In our previous study, we also demonstrated optically pumped GaN-based VCSELs by employing dielectric DBR VCSEL [26], [27] and hybrid DBR VCSEL structures [28], [29].…”