Long wavelength emitting GaInN quantum wells on metamorphic GaInN buffer layers with enlarged in-plane lattice parameter

Abstract

Metamorphic (i.e., linear composition graded) GaInN buffer layers with an increased in-plane lattice parameter, grown by plasma-assisted molecular beam epitaxy, were used as templates for metal organic vapor phase epitaxy (MOVPE) grown GaInN/GaInN quantum wells (QWs), emitting in the green to red spectral region. A composition pulling effect was observed allowing considerable higher growth temperatures for the QWs for a given In composition. The internal quantum efficiency (IQE) of the QWs was determined by temperature and excitation power density dependent photoluminescence (PL) spectroscopy. An increase in IQE by a factor of two was found for green emitting QWs grown on metamorphic GaInN buffer compared to reference samples grown on standard GaN buffer layers. The ratio of room temperature to low temperature intensity PL of the red emitting QWs were found to be comparable to the PL efficiency of green emitting QWs, both grown on metamorphic GaInN buffers. The excitation density and well width dependence of the IQE indicate a reduction of the quantum confined Stark effect upon growth on GaInN buffer layers with increased in-plane lattice parameter

Compliant Micron-Sized Patterned InGaN Pseudo-Substrates Utilizing Porous GaN

“…The enhanced indium uptake can be explained by the composition pulling effect, as the lower misfit strain on the tiles led to a higher indium incorporation in the regrown layer [9]. Interestingly, regrowth of the In y Ga 1−y N layer with a higher indium content (y = 0.145) than that of the In x Ga 1−x N layer underneath (x = 0.08) led to an increase in the degree of relaxation of the In x Ga 1−x N layer from 45% to~71% as shown in Figure 1f, corresponding to an increase of its 'a' lattice constant from 3.202 to 3.209 Å.…”

“…The misfit strain also leads to reduced indium incorporation through the so-called compositional pulling effect [4]. A suppression of the indium incorporation into compressively strained InGaN films compared to relaxed, strain-free InGaN was found in both experimental as well as thermodynamic studies [5][6][7][8][9][10]. Due to the reduced lattice mismatch between a relaxed InGaN buffer and the quantum wells (QWs), a higher indium incorporation efficiency can be achieved.…”

“…Attempts have been made to fabricate as-grown relaxed InGaN buffers on substrates such as ZnO [11][12][13] and ScAlMgO 4 [14,15]; however, the very low growth temperatures required for deposition on ZnO and the high n-type conductivity of InGaN grown on ScAlMgO 4 substrates have made metal-organic chemical vapor deposition (MOCVD) growth efforts on these substrates very challenging. Alternately, partially relaxed engineered InGaN substrates have been explored [6] and relaxed InGaN buffer layers have been fabricated by molecular-beam epitaxy (MBE) and used as pseudo substrates for MOCVD growth [9,16,17]. Attempts have also been undertaken to fabricate InGaN pseudo-substrates via coalescence of relaxed nano-feature arrays [18].…”

InGaN/Dilute-As GaNAs Interface Quantum Well for Red Emitters

“…Several approaches have been made to address the charge separation issue in blue and green QW LEDs 9 10 11 12 13 14 15 16 17 18 19 , including nonpolar/semipolar InGaN QW 9 , staggered InGaN QW 10 11 12 and InGaN QW with AlGaN delta-layer 13 14 . However, the approaches are not entirely applicable to addressing the issues in red QW LEDs since high In-content incorporation needs to be taken into consideration.…”

“…The efforts devoted on extending the nitride-based QW LED emission wavelength towards red spectral regime are still significantly lacking, albeit the research progress is picking up momentum lately. To date a number of approaches have been proposed to address the issues in red emitting GaN-based QW LEDs which include the InGaN metamorphic buffer layer or InGaN substrate for InGaN QW 18 19 , the InGaN-delta-InN QW 21 , InGaN with AlGaN interlayer QW 22 , Eu-doped GaN QW instead of InGaN QW 23 24 25 , lattice-relaxed InGaN multiple QW structure 26 and semipolar InGaN QW 27 . Note that most approaches in addressing red nitride QW LED are fairly similar to the approaches in addressing the blue and green nitride QW LEDs.…”