It is established that the formation of rotationally supported disks during the main accretion phase of star formation is suppressed by a moderately strong magnetic field in the ideal MHD limit. Non-ideal MHD effects are expected to weaken the magnetic braking, perhaps allowing the disk to reappear. We concentrate on one such effect, ambipolar diffusion, which enables the field lines to slip re...

The effect of nanoscale Pt islands on the electrical characteristics of contacts to p-type gallium nitride (GaN) has been investigated to explore the feasibility for the flip-chip configuration light-emitting diodes (LEDs) using an Al-based reflector. An as-deposited Al contact to p-GaN with a net hole concentration of 3 × 10 cm−3 was rectifying. However, an Al contact with nanoscale Pt islands...

Neutrino radiation takes a major role in the momentum, heat, and lepton transports in protoneutron stars (PNSs). These diffusive processes affect the growth of magnetorotational instability (MRI) in PNSs. We perform a local linear analysis for the axisymmetric and nonaxisymmetric MRI including the effects of neutrino transports and ohmic dissipation. We find that the MRI can grow even in the mu...

We report on ohmic contact measurements of Al, Au, and W metallizations to p-type epitaxial Ge0:9983C0:0017 grown on a (100) Si substrate by molecular beam epitaxy (MBE). Contacts were annealed at various temperatures, and values of specific contact resistance have been achieved which range from 10 5 cm2 to as low as 5:6 10 6 cm2. Theoretical calculations of the contact resistance of metals on ...

Cu-Mo and Cu-Ti contact structures were fabricated on multi-crystalline silicon substrates to provide a low resistance ohmic contact. Deposition steps are done in an excellent vacuum chamber by means of electron beam evaporation and samples are then annealed for the realization of an efficient alloy layer. The effects of process parameters such as film thickness, annealing duration and temp...

A low-resistance ohmic contact to Mg-doped p-type GaN grown by metal-organic chemical vapor deposition (MOCVD) with a carrier concentration of 2 · 10 cm 3 using Pd/Ni/Au metallization was formed. An anneal at 500 C for 1 min in a flowing N2 ambient produced an excellent ohmic contact with a specific contact resistivity as low as 2.4 · 10 5 X cm. X-ray photoelectron spectroscopy (XPS) and Auger ...