Homoepitaxial growth of ZnO films with reduced impurity concentrations by helicon-wave-excited-plasma sputtering epitaxy using a crystalline ZnO target prepared by hydrothermal technique

Abstract

Heat dissipation is one of the most important issues for the reliability of electronic equipment. Boiling can be a very efficient heat transfer mechanism when used to face with the electronic technology needs of efficient and compact heat sinks. Recently, cellular structured materials both stochastic and periodic, particularly open cell metal foams, have been proposed as possible enhanced surfaces to lower the junction temperatures at high heat fluxes. Up today, most of the research on metal foams only regards single phase flow, whereas the two phase flow is still almost unexplored. This paper presents an experimental study on the heat transfer of R134a during flow boiling inside a 5 PPI (Pores Per linear Inch) copper foam, which is 5 mm high, 10 mm wide and 200 mm long, and it is brazed on a 10 mm thick copper plate. The experimental measurements were carried out by imposing three different heat fluxes (50, 75, and 100 kW m -2 ) and by varying the refrigerant mass velocity between 50 and 200 kg m -2 s -1 and the vapour quality from 0.2 to 0.90, at constant saturation temperature (30°C). The effects of the refrigerant mass flow rate, heat flux and vapour quality on the heat transfer coefficient, dry out phenomenon, and pressure drop are studied.

Formation of shallow boron emitters in crystalline silicon using flash lamp annealing: Role of excess silicon interstitials

“…The superior quality of hetero-and homoepitaxial thin films compared to polycrystalline ones enables advanced characterization of the epilayers and the improved properties of the thin films can reveal elusive information on defect properties [71], carrier scattering mechanisms [66,72], carrier generation [73] and recombination mechanisms [74].…”

Controlling the carrier lifetime of nearly threading-dislocation-free ZnO homoepitaxial films by 3d transition-metal doping

“…Approximately 300 to 1400-nm-thick, (0001) Zn-polar TM-doped ZnO epilayers 24 were grown by the heliconwave-excited-plasma sputtering epitaxy (HWPSE) method 25 by sputtering a 50-mm-diam. polycrystalline or (0001) Znpolar crystalline ZnO target on a 500-lm-thick (0001) Znpolar ZnO substrate.…”

“…polycrystalline or (0001) Znpolar crystalline ZnO target on a 500-lm-thick (0001) Znpolar ZnO substrate. We used this method, because it can grow nearly TD-free (<10 5 cm À2 ) ZnO epitaxial films exhibiting atomically smooth surface morphology with 0.25-nmhigh monolayer atomic step lines, 24,26 and thus any possible interferences by TDs can be eliminated. As a matter of fact, all the samples exhibited well-aligned monolayer atomic step lines and TD density was less than 10 5 cm À2 .…”

“…As a matter of fact, all the samples exhibited well-aligned monolayer atomic step lines and TD density was less than 10 5 cm À2 . 24 The polycrystalline target was grown by the chemical vapor transport (CVT) technique (Eagle Picher), 27 while the substrate and the crystalline target were grown by HT technique (Tokyo Denpa). 10 The Li impurities originating from the mineralizer used in the HT process were out-diffused from their surfaces using high temperature annealing.…”

“…The concentrations of B, C, Cr, Li, and Si were lower than the detection limits, and the PL peaks peculiar to B, Ga, and In shallow donors 29,30 were not detected. 24 The concentrations of Ni and Mn and residual Fe and Al are summarized in Table I. The sample identification (ID) numbers N1 $ N6 are given following the order of increasing [TM] being 3 Â 10 17 to 4 Â 10 18 cm À3 .…”