The Al-doped ZnO (AZO) films doped with different indium concentrations were grown on glass substrates (Corning 1737) at 200 °C by pulsed laser deposition. Indium doping in AZO films shows a critical effect on the crystallinity, resistivity and optical properties of the films. The AZO films doped with 0.3 atom% indium content exhibit the highest crystallinity, the lowest resistivity of 4.5 × 10−4 Ω cm and the maximum transmittance of 93%. The crystallinity of the indium doped-AZO films is strongly related to the resistivity of the films. The carrier concentration in the indium doped-AZO films linearly increases with increasing indium concentration. The mobility of the AZO films with increasing indium concentration was reduced with an increase in the carrier concentration and the decrease in mobility was attributed to the ionized impurity scattering mechanism. In optical transmittance, the shift of the optical absorption edge to a shorter wavelength strongly depends on the electronic carrier concentration in the films. The figure of merit FTC used for evaluating transparent electrodes reached 0.32 Ω−1 at 550 nm wavelength.

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 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 InGaN layers on GaN templated sapphire (0001) and Si (111) substrates are grown by mixed-source hydride vapor phase epitaxy (HVPE) method. As a new attempt in obtaining an InGaN layers, the growth of the thick InGaN layer is performed by putting small amount of Ga into the In source. The InGaN layer is compounded from chemical reaction between a NH 3 and an Indium-gallium chloride formed by HCl flown over metallic In mixed with Ga. The InGaN layer is analyzed by X-ray photoelectron spectroscopy (XPS) to characterize the InGaN ternary crystal alloy. The optical property of the selective area growth (SAG) of the InGaN layer is investigated by the photoluminescence (PL) spectrum and the cathodoluminescence (CL) images. Indium compositions are estimated to be in the range 3-10 %. In order to obtain the GaN layer on GaN templated Si (111)