arXiv subjects

H. P. Wei

Publications and source records attributed to H. P. Wei.

3 recordsLinked to original sources

arXiv2000

Evidence For Heavy Hole and Light Hole Current Separation in P-Type Resonant Tunneling Diodes With Prewells

We investigate the transport of holes through $AlAs/In_{.10}Ga_{.90}As$ resonant tunneling diodes which utilize $In_xGa_{1-x}As$ prewells in the emitter with $x=0,.10,$ and $.20$. The data show an increase in peak current and bias at resonance and a concurrent increase in the peak-to-valley ratio with increasing x. We explain this enhancement in tunneling as due to confinement (or localiz- ation) of charges in the prewell and the formation of direct heavy(light) hole to heavy(light) hole conduction channels as a consequence.

cond-mat.mes-hall↗

arXiv1998

Probing the plateau-insulator quantum phase transition in the quantum Hall regime

We report quantum Hall experiments on the plateau-insulator transition in a low mobility In_{.53} Ga_{.47} As/InP heterostructure. The data for the longitudinal resistance ρ_{xx} follow an exponential law and we extract a critical exponent κ= .55 \pm .05 which is slightly different from the established value κ= .42 \pm .04 for the plateau transitions. Upon correction for inhomogeneity effects, which cause the critical conductance σ_{xx}^* to depend marginally on temperature, our data indicate that the plateau-plateau and plateau- insulator transitions are in the same universality class.

cond-mat.mes-hall↗

arXiv1996

Phonon Emission from a 2D Electron Gas: Evidence of Transition to the Hydrodynamic Regime

Using as a thermometer the temperature dependent magneto-transport of a two-dimensional electron gas, we find that effective temperature scales with current as $T_{\rm e} \sim I^a$, where $a=0.4 \pm 2\%$ in the {\it Shubnikov de-Haas} regime, and $0.53 \pm 2\%$ in both the {\it integer and fractional} quantum Hall effect. This implies the phonon energy emission rate changes from the expected $P\sim T^5$ to $P\sim T^4$. We explain this, as well as the dramatic enhancement in phonon emission efficiency using a hydrodynamic model.

cond-mat↗