Characterization of AlGaN/InGaN/AlGaN heterostructure with selective area growth of Te‐doped AlGaN cladding layer grown by mixed‐source HVPE

Abstract

The selective area growth (SAG) of AlGaN/InGaN/AlGaN light-emitting diodes (LEDs) is performed by mixed-source hydride vapor phase epitaxy (HVPE). The structure is grown on a n-GaN templated (0001) sapphire substrate. The SAG-double heterostructure (DH) is consisted of a Te-doped AlGaN cladding layer, an InGaN active layer, a Mg-doped AlGaN cladding layer, and a Mg-doped GaN capping layer. All of the epitaxial layers of LED structure are grown consecutively with a multi-sliding boat system. Roomtemperature electroluminescence (EL) characteristics show an emission peak wavelength of 400 nm with a full width at half-maximum (FWHM) of approximately 0.38 eV (at 20 mA). We find that the mixedsource HVPE method with multi-sliding boat system is possible to be one of the growth methods of IIInitride LEDs. HVPE is allowed the growth of low defect density material that incorporates a high proportion of aluminium (Al) in the AlGaN layers without severely degrading the crystal quality [4]. In addition, the HVPE process is also a "carbon-free" technology, as gaseous hydrogen chloride (HCl) used in the epitaxial layer growth provides an impurity self-cleaning effect. These result in low background material contamination, more efficient doping, and high internal quantum efficiency of radiative recombination in HVPE-LED structures [5]. However HVPE method is difficult to grow thin films and multilayer structures. Several attempts to grow multilayer structures by HVPE method have been reported. Lam et al. report that multilayer structure is grown by HVPE with multichannel gas distribution system [6].SAG is already well known to reduce the dislocation density by blocking the dislocation propagation from the substrate using the oxide mask [7][8][9]. Moreover, the SAG technique causes less damage and contamination than the dry etching.

Fabrication of selective-area growth InGaN LED by mixed-source hydride vapor-phase epitaxy

“…Source gases such as HCl, N 2 , and NH 3 were jetted through two quartz tubes for the growth of the epilayers. [23][24][25][26][27][28][29][30][31] Table I shows the growth conditions and measured results of epilayers consisting of a bare chip with an In composition of 11.0% in the active layer. By using a multi-graphite boat filled with the mixed source of In and Ga, the SAG epilayers were deposited by the mixed-source HVPE method on an n-type GaN substrate to fabricate the SAG InGaN LEDs.…”

“…The setup is different from that of previously reported HVPE methods. [23][24][25][26][27][28][29][30][31] The fabrication of the LED by the mixedsource HVPE method is based on the consecutive growth of all epitaxial layers using a multi-graphite boat filled sequentially with mixed-source materials in the source zone at high temperatures (T > 900 °C). 23) This mixed-source HVPE method has the advantages of low manufacturing cost owing to the reduced number of manufacturing steps, consecutive growth of epilayers using the multi-graphite boat, and ease of doping by regulating the mixing ratio of source materials.…”