The AlxGa1–xN layers on GaN/Al2O3 substrates are grown by mixed‐source hydride vapor phase epitaxy (HVPE) at various temperatures of the source zone. We find source zone temperature dependence of the composition x of AlxGa1–xN layers. Te doping as a new attempt and Si doping in obtaining an n‐type AlGaN layers are performed by putting small amount of Te (or Si) into the Ga‐Al source, respectively. In case of Te‐doped AlGaN (x = 0.16), the carrier concentration is varied from 1.1 x 1018 to 8.0 x 1018/cm3, while in case of Si‐doped one, it is varied from 2.0 x 1016 to 1.1 x 1017/cm3. We find the new results that Te doping is more suitable to get a high n‐type concentration by mixed‐source HVPE. InGaN/GaN multiple quantum wells (MQWs) are grown on the selective area growth (SAG)‐Te‐doped AlGaN and SAG‐Si‐doped AlGaN cladding layer by mealorganic chemical vapour deposition (MOCVD), respectively. Furthermore, we investigate the electroluminescence (EL) properties of SAG‐LEDs of two different cladding layers. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The growth of a thick AlGaN is performed on Al 2 O 3 substrate by metalorganic vapor phase epitaxyhydride vapor phase epitaxy (MOVPE-HVPE) combined system. Thin AlN or GaN layer is grown on a substrate by MOVPE growth method with the conventional manner but in a hot-wall chamber and followed by the HVPE growth of a thick AlGaN in the same chamber. For the growth of a AlGaN layer, NH 3 and aluminum-gallium chloride formed by HCl which is flown over metallic Ga mixed with Al are used as aluminum-gallium and nitrogen sources. The peak of the cathodoluminescence (CL) spectrum of the thick AlGaN is shown at the wavelength of 354 nm. This suggests that the metallic Ga mixed with Al can be used as a group III source material in the HVPE growth of the AlGaN.

The selective area growth (SAG) of AlGaN/InGaN/AlGaN light-emitting diodes (LEDs) is performed by mixed-source hydride vapor phase epitaxy (HVPE). In order to obtain the SAG-AlGaN/InGaN/AlGaN heterostructure, a special graphite fixture to use in HVPE is designed. First, an n-type AlGaN layer is grown at 1090 °C on a GaN templated (0001) sapphire substrate with a patterned SAG-structure of a silicon oxide (SiO 2 ). On this selectively grown n-type AlGaN layer, a nominally undoped-InGaN layer is grown using an In-Ga mixed metallic source at 990 °C. After the growth of InGaN layer, Mg-doped AlGaN and Mg-doped GaN layers are grown as a cladding and capping layers at 1090 °C and 1050 °C, respectively. All of the epitaxial layers of LED structure are grown consecutively with a multi-sliding boat system. Room-temperature electroluminescence (EL) characteristics show an emission peak wavelength of 415 nm with a full width at half-maximum (FWHM) of approximately 0.37 eV. We find that the mixed-source HVPE method with multi-sliding boat system is possible to be one of the growth methods of III-nitride LEDs. . However, HVPE method has performed an important role to provide III-nitride substrates because of its high growth rate and low growth cost. Recently, multilayer structures were grown by HVPE method with multichannel gas distribution system [5]. The high internal quantum efficiency of radiative recombination in HVPE-grown LED structure is related to the low impurity contamination by the impurity-cleaning effect of gaseous HCl and carbon free technology [6].Among the various methods to fabricate LEDs, a SAG method can improve the crystal quality with low dislocation density because the dislocation propagation from the substrate is blocked by the oxide mask [7][8][9]. Moreover, the SAG technique causes less damage or less contamination than the dry etching technique. Usui et al. reported that the ELO-GaN layer formed by HVPE with a SiO 2 mask contains a dislocation density as low as 10 7 /cm 2 [10]. In this paper, we report on the new mixed-source HVPE growth method with multi-sliding boat system. Each layer of the SAG-AlGaN/InGaN/AlGaN LED is grown by a chemical reaction of NH 3 , HCl

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.

The AlxGa1–xN, Te‐doped GaN and Mg‐doped GaN layers on GaN/Al2O3 substrates are grown by mixed‐source hydride vapor phase epitaxy (HVPE) method. The metallic Ga mixed with Al is used as group III source material to get the AlxGa1–xN layers. The values of the compositions x of the AlxGa1–xN layers characterized by X‐ray diffraction (XRD) measurements are 0.6% ∼ 80% at the various temperatures of the source zone. The metallic Ga mixed with Te (or Mg) is used as source material for n‐type (or p‐type) doping. The electron concentrations of the Te‐doped GaN layers are varied from 1.8 × 1017 to 8.3 × 1018/cm3. The hole concentrations of the Mg‐doped GaN layers are varied from 1.5 × 1016 to 3.2 × 1016/cm3. We find that the mixed‐source HVPE method is suitable to get a thick AlGaN layer with an arbitrary composition, a Te‐doped GaN layer with a high n‐type concentration and a Mg‐doped GaN layer with p‐type concentration. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)