TMIn Flow Research Articles

Effects of TMIn flow on the interface and optical properties of InGaN/GaN mutiple quantum wells

The effects of pre-TMIn flow prior to QW growth and TMIn flow rates during QW growth on the interface and optical properties of InGaN/GaN MQWs were investigated. Pre-depositing indium prior to QW growth and an appropriate TMIn flow rate can improve the interface abruptness and increase the EL intensity. InGaN/GaN MQWs with improved interface abruptness have increasing emission intensity and wavelength. We attribute the interface improvement and the increase of EL intensity to the improvement of the indium compositional profiles.

Effect of the ratio of TMIn flow to group Ⅲ flow on the properties of InGaN/GaN multiple quantum wells

Triple-axis x-ray diffraction (TXRD) and photoluminescence (PL) spectra are used to assess the influence of the ratio of TMIn flow to group Ⅲ flow on structural defects, such as dislocations and interface roughness, and optical properties of multiple quantum wells(MQWs). In this paper the mean densities of edge and screw dislocations in InGaN/GaN MQWs are obtained by ωscan of every satellite peak of (0002) symmetric and (1012) asymmetric diffractions. At the same time, the interface roughness is measured by the radio of the full width at half maximum of satellite peaks to the peak orders. The experimental results showed that the density of dislocation, especially of edge dislocation, and interface roughness increase with the increase of the ratio, which leads to the decrease of PL properties. It also can be concluded that the edge dislocation acts as nonradiative recombination centers in InGaN/GaN MQWs. Also noticed is that the variation of the ratio has more influence on edge dislocation than on screw dislocation.

The Effect of MOCVD Growth Parameters on the Photolumenescence Intensity of InN/GaN Multi-layers

InN/GaN multi-layers were grown by metalorganic chemical vapor deposition(MOCVD) in order to get the appropriate structure for an high power blue-green light emitting diode(LED), and effects of growth conditions (growth temperature, pressure, and on the integrated photoluminescence (PL) intensity and PL peak energy in InN/GaN multi-layers were investigated. The optimized growth conditions with the highest integrated PL intensity for InN/GaN multi-layers were obtained: the growth temperature at , the growth pressure at 325 Torr, the TMIn flow rate with 150 /min, the flow rate with 3.2 ι/min, and flow rate with 2 ι/min.

Effect on the optical properties and surface morphology of cubic GaN grown by metalorganic chemical vapor deposition using isoelectronic indium surfactant doping

The surfactant effect of isoelectronic indium doping during metalorganic chemical vapor deposition growth of cubic GaN on GaAs (1 0 0) substrates was studied. Its influence on the optical properties and surface morphology was investigated by using room-temperature photoluminescence (PL) and atomic force microscopy. It is shown that the sample with small amount of In-doping has a narrower PL linewidth, and a smoother surface than undoped cubic GaN layers. A slight red shift of the near-band-edge emission peak was observed. These results revealed that, for small TMIn flow rates, indium played the role of the surfactant doping and effectively improved the cubic GaN film quality; for large TMIn flow rates, the alloying formation of Ga 1− x In x N might have occurred.

Growth mode transition of InGaAs in OMVPE growth on GaP (001)

We investigated growth of InGaAs with different In compositions on GaP (001) substrates by low-pressure organometallic vapor phase epitaxy (LP-OMVPE). From atomic force microscope (AFM), plan-view transmission electron microscope (TEM), cross-sectional TEM and high-resolution TEM observations, it was found that the growth depended clearly on the ratio of TMIn flow rate to the total flow rate of group-III sources ( x TMIn). In the low x TMIn region, InGaAs grew as a layer. In the high x TMIn region, on the other hand, island formation took place. At x TMIn=0.5, InGaAs islands were formed by the Stranski–Krastanow (S–K) growth mode.

Growth of In xGa 1− xN thin films on indium tin oxide/glass substrates by RF plasma enhanced chemical vapor deposition

In x Ga 1− x N thin films with GaN buffer layers (200°C) were grown on indium tin oxide (ITO)/glass substrates at 500°C by RF plasma enhanced chemical vapor deposition (PECVD). Preferred (0002) and (10 1 1) directions of the samples and successful incorporation of In with TMIn flow rate were characterized by X-ray diffraction (XRD). Results of the optical absorption measurements showed that the absorption band edges shifted to the lower energy with increasing In solid compositions. Atomic force microscopy (AFM) showed the lumps of grains tended to be larger with In solid composition although the surface deteriorated.

Detailed analysis of carrier transport in InAs0.3Sb0.7 layers grown on GaAs substrates by metalorganic chemical-vapor deposition

InAs0.3Sb0.7 layers with mirrorlike morphology have been grown on GaAs substrates by low-pressure metalorganic chemical vapor deposition. A room-temperature electron Hall mobility of 2×104 cm2/V s has been obtained for a 2-μm-thick layer. Low-temperature resistivity of the layers depended on TMIn flow rate and layer thickness. Hall mobility decreased monotonically with decreasing temperature below 300 K. A 77 K conductivity profile has shown an anomalous increase in the sample conductivity with decreasing thickness except in the near vicinity of the heterointerface. In order to interpret the experimental data, the effects of different scattering mechanisms on carrier mobility have been calculated, and the influences of the lattice mismatch and surface conduction on the Hall measurements have been investigated by applying a three-layer Hall-effect model. Experimental and theoretical results suggest that the combined effects of the dislocations generated by the large lattice mismatch and strong surface inversion may lead to deceptive Hall measurements by reflecting typical n-type behavior for a p-type sample, and the measured carrier concentration may considerably be affected by the surface conduction up to near room temperature. A quantitative analysis of dislocation scattering has shown significant degradation in electron mobility for dislocation densities above 107 cm−2. The effects of dislocation scattering on hole mobility have been found to be less severe. It has also been observed that there is a critical epilayer thickness (∼1 μm) below which the surface electron mobility is limited by dislocation scattering.

Effects of Growth Conditions and Substrate Orientation on the Properties of InSb

AbstractTwo new organometallic Sb sources, tris(dimethylamino)antimony (TDMASb), and tertiarybutyldimethylantimony (TBDMSb) are being investigated. The growth of InSb using TDMASb, or TBDMSb and TMIn was investigated over a temperature range of 350 to 475 °C using a range of V/III ratios, growth rates and pressures. Misoriented InSb substrates were also used for selected growth conditions The growth rates of lnSb using TMIn and either TDMASb or TBDMSb at temperatures <= 425 °C were proportional to both the TMIn flow rate and the temperature. The surface morphology of InSb grown using either TDMASb or TBDMSb was very rough for growth temperatures <=425 °C. This may be due to the complex decomposition mechanisms involved and the presence of methyl groups on the surface. Smoother backgrounds were generally found when using off axis substrates. The details of the defects observed on the surfaces were dependent on the type of misorientation and can be related to the atomic structure of the surface steps. Both n- and p-type InSb were grown using TBDMSb or TDMASb and TMIn with mobilities up to 68,990 and 7773 cm2/Vs, respectively, at 77 K. The mobility for lnSb using either TDMASb or TBDMSb was optimized by going to lower temperatures, pressures and V/III ratios. The opposite was true for surface morphology which improved with higher temperature, pressure, and V/III ratio. The growth of high mobility InSb with smooth surfaces at T< =425 °C was not achieved with TDMASb or TBDMSb and TMIn under the conditions investigated in this work.

The growth of InSb using triisopropylantimony or tertiarybutyldimethylantimony and trimethylindium

The growth of InSb using triisopropylantimony (TIPSb) or tertiarybutyldimethylantimony (TBDMSb) and TMIn was investigated over a temperature range of 350 to 475°C. The growth rates of InSb using TMIn and either TIPSb or TBDMSb at temperatures ≤425°C were proportional to both the TMIn flow rate and the temperature. The surface morphology of InSb grown using either TIPSb or TBDMSb was very rough for growth temperatures ≤425°C. The InSb with the highest mobility was grown at 400°C and a 5/3 ratio of 3 using TIPSb. It was n-type with a carrier concentration of 2.5 × 10 15 cm -3 and a mobility of 78,160 cm 2/V·s at 77 K. Both n- and p-type InSb were grown using TBDMSb with mobilities up to 67,530 and 7773 cm 2/V·s, respectively at 77 K. The mobility for InSb using either TIPSb or TBDMSb was optimized by going to lower temperatures, pressures and 5/3 ratios. The opposite was true for surface morphology which improved with higher temperature, pressure, and 5/3 ratio. The growth of high mobility InSb with smooth surfacestat T ≤ 425° C was not achievable with TIPSb or TBDMSb and TMIn.

Effects of growth parameters on layer properties for InP and related alloys grown by MOCVD

The effects of group-V and group-III source flow rates on epi-layer properties have been studied for the MOCVD growth of InP and GaInPAs. For InP, the surface morphology and photoluminescence (PL) intensity were almost completely determined by PH3 flow rate, independent of TMIn flow rate. On the other hand, the PL full width at half maximum (FWHM) and electron mobility were determined by the VIII ratio. The carrier concentration of Se-doped InP was unchanged by both PH3 and TMIn flow rate, differing from that of Se-doped GaAs. The composition ratio of As to P for GaInPAs was mainly determined by the flow ratio of AsH3 to PH3, but affected by the total group-V flow rate (AsH3+PH3) and by the group-III alloy composition. It was found that the absolute PH3 pressure in the vapor phase was one of the most important growth parameters in determining the epi-layer properties.