Characterization of AlInGaN quaternary epilayers grown by metal organic chemical vapor deposition

Growth behavior of AlInGaN films

“…2(b) have the same in-plane lattice constant, and there is a large lattice-mismatch between AlInGaN and GaN. In this case, the well-known composition-pulling effect is unavoidable and the Al composition will exhibit a gradual increase with increasing the film thickness [13]. In other words, the Al composition becomes larger at the surface, which causes a smaller c-axis length (c_GaN ¼ 0.5185 nm, c_AlN ¼ 0.498 nm, c_InN ¼ 0.57 nm).…”

High Al-content AlInGaN epilayers with different thicknesses grown on GaN/sapphire templates

“…Thus, the increase of Al-content in the compositionstable region is likely to contribute much to this blue shift. It is worth noting that the relaxation of tensile strain can also contribute to the PL blue shift [14]. It is believed that, at a given high Al-content (>0.4) and low In-content (0.003-0.016), the relaxation of elastic energy in AlInGaN epilayer will occur by cracks when the critical thickness (h crit ) is reached, referring to the similar phenomenon reported in AlGaN epilayers grown on GaN templates [19,20].…”

“…Compared with conventional AlGaN materials used in various devices, AlInGaN epilayers can provide more choices of adjusting lattice constants and band gaps independently, which is important to reduce the dislocation density and piezoelectric effect in nitride heterostructures. Some studies on the growth procedure and material properties of AlInGaN epilayers have been done in recent years [8][9][10][11][12][13][14]. In particular, thickness-dependent properties of low Al-content AlInGaN epilayers have aroused much interest.…”

“…In particular, thickness-dependent properties of low Al-content AlInGaN epilayers have aroused much interest. For instance, Liu et al [14,15] reported the increase of Al-content with the thickness of low Al-content (<0.15) AlInGaN epilayers, which was attributed to composition pulling effect (CPE). Similar phenomena were also reported in InGaN [16,17] and AlGaN [18] epilayers on GaN.…”

Nitride‐based light emitting diodes with quaternary p‐AlInGaN surface layers

“…In other words, we might be able to enhance the LED output intensity by changing surface morphology of LEDs. Previously, it has been shown that surface morphology of AlInGaN layers is rough [5][6][7][8]. Thus, we might be able to enhance LED output intensity by using p-AlInGaN to replace p-GaN as the surface layer of nitride-based LEDs.…”