The Experts below are selected from a list of 66 Experts worldwide ranked by ideXlab platform

J A Del Alamo - One of the best experts on this subject based on the ideXlab platform.

  • critical voltage for electrical degradation of gan high electron mobility transistors
    IEEE Electron Device Letters, 2008
    Co-Authors: J A Del Alamo
    Abstract:

    We have found that there is a critical drain-to-gate voltage beyond which GaN high-electron mobility transistors start to degrade in electrical-stress experiments. The critical voltage depends on the detailed voltage biasing of the device during electrical stress. It is higher in the OFF state and high-power state than at VDS = 0. In addition, as |VGS| increases, the critical voltage decreases. We have also found that the stress current does not affect the critical voltage although soft degradation at low voltages takes place at high stress currents. All of our findings are consistent with a degradation mechanism based on Crystallographic-Defect formation due to the inverse piezoelectric effect. Hot-electron-based mechanisms seem to be in contradiction with our experimental results.

G.r. Booker - One of the best experts on this subject based on the ideXlab platform.

  • Crystallographic Defect studies in SIMOX material thinned by sacrificial oxidation
    Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 1994
    Co-Authors: L.f. Giles, C.d. Marsh, A. Nejim, P.l.f. Hemment, G.r. Booker
    Abstract:

    Abstract Crystallographic Defects present in thermal oxidised SIMOX materials have been studied by means of plan view transmission electron microscopy (TEM) and chemical Defect etching. It is observed that the presence of small stacking fault tetrahedra near the top Si/SiO2 interface influence the formation of oxidation induced stacking faults (OISF). An explanation for this behaviour is given based on the assumption that these small Crystallographic Defects contribute to the recombination of silicon interstitials emitted during thermal oxidation.

  • characterization of the Crystallographic Defect structure in selected area epitaxial growth of gainas on inp by metallo organic chemical vapour deposition
    Materials Science and Engineering B-advanced Functional Solid-state Materials, 1993
    Co-Authors: R E Mallard, E J Thrush, M A Gibbon, G.r. Booker
    Abstract:

    Abstract We describe the chemical and Crystallographic structure of selected-area metallo-organic chemical vapour deposition overgrowths of InP and GaInAs on partially masked (100) InP substrates, using energy-dispersive X-ray analysis, transmission electron microscopy and high resolution electron microscopy. The presence of the oxide mask, which specifies the selected areas for epitaxial deposition, has the effect of perturbing the gas flow over the wafer surface, which can induce a modification of the local composition and morphology of the depositing material and result in the incorporation of interfacial misfit stresses. High densities of interfacial misfit dislocations are observed in material in which this perturbation is greatest. The majority of the dislocations in the planar epitaxial regions have a 60° character, but in the highly mismatched and facetted regions of growth adjacent to the mask edges, a variety of novel misfit-relieving dislocation structures are observed and these are identified by high resolution electron microscopy.

Nobuo Miyamoto - One of the best experts on this subject based on the ideXlab platform.

  • surface adsorbate related nucleation of Crystallographic Defect in chemical vapor deposition of silicon with dichlorosilane
    Applied Surface Science, 1997
    Co-Authors: Yuji Takakuwa, Motaharul Kabir Mazumder, Nobuo Miyamoto
    Abstract:

    Abstract In atmospheric chemical vapor deposition of silicon with H2-diluted SiH2Cl2 on Si(111), the kinetics of Defect nucleation for stacking fault, dislocation and poly-Si was investigated as a function of growth temperature and SiH2Cl2 flow rate. In comparison to an Arrhenius plot of growth rate, it was observed that stacking fault and dislocation are nucleated appreciably in the surface-reaction rate-limited temperature region. Moreover, we found that the stacking fault density increased as a parabolic function of SiH2Cl2 volume concentration, cvol, and the dislocation density increased almost linearly with cvol, while no significant increase was then observed for the poly-Si density. The stacking fault and dislocation densities had the almost same incubation cvol below which no Defects appeared. These observations indicate that the surface adsorbate gives rise to the nucleation of stacking fault and dislocation and the surface adsorbate related nucleation mechanism of stacking fault is different from that of dislocation.

  • generation kinetics of pyramidal hillock and Crystallographic Defect on si 111 vicinal surfaces grown with sih2cl2
    Journal of Crystal Growth, 1995
    Co-Authors: M K Mazumder, Yoji Mashiko, M H Koyama, Yuji Takakuwa, Nobuo Miyamoto
    Abstract:

    Abstract The generation kinetics and surface morphology of Crystallographic Defects were investigated on Si(111) vicinal surfaces grown with SiH 2 Cl 2 . By chemical etching observation, it was found that on the Si(111) 0° off surface with a small misorientation angle the Crystallographic Defect always develops as a pyramidal hillock with different apex morphology depending on the type of Defect. Dislocations, stacking faults and polycrystalline Si are associated with hillocks with sharp and flat apexes and bright particles, respectively. On the other hand, no hillocks were observed on the Si(111) 4° off surface with a large step density irrespective of the existence of such Defects. This drastic change of the surface morphology of the Crystallographic Defect indicates that the Crystallographic Defect can play the role of growth nucleus of the hillock with a large growth rate on the Si(111) 0° off surface, leading to the growth of a triangular hillock independent of the type of Defect. Therefore, without chemical etching of the as-grown surface, the pyramidal hillock can be employed as a finger print of a Crystallographic Defect, whose type is distinguished by giving attention to its apex morphology. Furthermore, the Crystallographic Defect generation was observed to be hardly affected by increasing step density in spite of the drastic disappearance of the corresponding hillock.

Yuji Takakuwa - One of the best experts on this subject based on the ideXlab platform.

  • surface adsorbate related nucleation of Crystallographic Defect in chemical vapor deposition of silicon with dichlorosilane
    Applied Surface Science, 1997
    Co-Authors: Yuji Takakuwa, Motaharul Kabir Mazumder, Nobuo Miyamoto
    Abstract:

    Abstract In atmospheric chemical vapor deposition of silicon with H2-diluted SiH2Cl2 on Si(111), the kinetics of Defect nucleation for stacking fault, dislocation and poly-Si was investigated as a function of growth temperature and SiH2Cl2 flow rate. In comparison to an Arrhenius plot of growth rate, it was observed that stacking fault and dislocation are nucleated appreciably in the surface-reaction rate-limited temperature region. Moreover, we found that the stacking fault density increased as a parabolic function of SiH2Cl2 volume concentration, cvol, and the dislocation density increased almost linearly with cvol, while no significant increase was then observed for the poly-Si density. The stacking fault and dislocation densities had the almost same incubation cvol below which no Defects appeared. These observations indicate that the surface adsorbate gives rise to the nucleation of stacking fault and dislocation and the surface adsorbate related nucleation mechanism of stacking fault is different from that of dislocation.

  • generation kinetics of pyramidal hillock and Crystallographic Defect on si 111 vicinal surfaces grown with sih2cl2
    Journal of Crystal Growth, 1995
    Co-Authors: M K Mazumder, Yoji Mashiko, M H Koyama, Yuji Takakuwa, Nobuo Miyamoto
    Abstract:

    Abstract The generation kinetics and surface morphology of Crystallographic Defects were investigated on Si(111) vicinal surfaces grown with SiH 2 Cl 2 . By chemical etching observation, it was found that on the Si(111) 0° off surface with a small misorientation angle the Crystallographic Defect always develops as a pyramidal hillock with different apex morphology depending on the type of Defect. Dislocations, stacking faults and polycrystalline Si are associated with hillocks with sharp and flat apexes and bright particles, respectively. On the other hand, no hillocks were observed on the Si(111) 4° off surface with a large step density irrespective of the existence of such Defects. This drastic change of the surface morphology of the Crystallographic Defect indicates that the Crystallographic Defect can play the role of growth nucleus of the hillock with a large growth rate on the Si(111) 0° off surface, leading to the growth of a triangular hillock independent of the type of Defect. Therefore, without chemical etching of the as-grown surface, the pyramidal hillock can be employed as a finger print of a Crystallographic Defect, whose type is distinguished by giving attention to its apex morphology. Furthermore, the Crystallographic Defect generation was observed to be hardly affected by increasing step density in spite of the drastic disappearance of the corresponding hillock.

P.l.f. Hemment - One of the best experts on this subject based on the ideXlab platform.