AlGaN-based MQWs grown on a thick relaxed AlGaN buffer on AlN templates emitting at 285 nm

Abstract

International audienceWe report on the growth of Al 0.57 Ga 0.43 N/Al 0.38 Ga 0.63 N MQWs grown on a relaxed Al 0.58 Ga 0.42 N buffer on AlN template by Metal Organic Vapor Phase Epitaxy. The MQW structure is designed so that the strain in the quantum wells induced by their lattice mismatch with barriers is sufficient to enhance TE polarized emission (E-field ⊥ c). A 630-nm thick relaxed Al 0.58 Ga 0.42 N buffer grown on AlN template serves as a pseudo-substrate to release the strain in the barriers and to avoid related defects or composition fluctuation in the active region. Thin (< 2 nm) quantum wells allow preservation of the overlapping of electron and hole wavefunctions considering the strong quantum-confined Stark effect in AlGaN-based MQW structures. Scanning transmission electron microscopy (STEM) coupled to energy-dispersive X-ray spectroscopy (EDX) analysis is used to optimize the growth conditions and to determine the composition of wells and barriers. Optical characterizations of the grown structure reveal a well-defined band-edge emission peak at 285 nm. Based on macro-transmission measurements and simulations, the absorption coefficient of the wells is estimated to be 3 × 10 5 cm −1 (E-field ⊥ c), attesting that the oscillator strength is preserved for these AlGaN MQWs with high Al content, which is promising for efficient surface-emitting devices in the deep ultra-violet (DUV) region

85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering

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GaN/AlGaN multiple quantum wells grown on transparent and conductive (-201)-oriented β-Ga2O3 substrate for UV vertical light emitting devices

“…When the precursor flow is interrupted during MOCVD growth, desorption of Ga atoms can occur due to the high temperature required for growth. 21 Following this layer, well-defined GaN/AlGaN MQWs are observed. The average thicknesses of the MQWs and MQBs are 3.2 nm and 10.3 nm, respectively.…”

Alteration of structural and optical properties in quaternary Al0.1In0.1Ga0.8N films using ultraviolet assisted photo-electrochemical etching route

“…Keeping pace with research and investigation carried out thus far on the III-nitrides semiconductors, stemming from binary GaN to ternary Al x Ga 1-x N and In y Ga 1-y N [11][12][13][14][15][16][17], as well as quaternary Al x In y Ga 1-x-y N [18][19][20], significance of growing optimum III-nitrides heterostructures for quantum wells with regards to the LEDs performance is unveiled.…”

“…In addition, it was observed from the Raman spectra that the intensity Of the optical phonon modes, the E 2 (high) mode peak shift was related to the in-plane biaxial stress relaxation [74]. The in-plane stress relaxation can be calculated according to the relation between the biaxial stress and Raman shift using the following expression [75] ∆ԝE 2 (high)= K R σ (12) M A N U S C R I P T…”