Encyclopedia of Applied Physics, Volume 22

2DEG absorption acoustic applications atoms band base beam bias bipolar transistor Boltzmann equation capacitance carrier ceramic channel characteristic circuit coefficient collector components constant core crystal density device diode dopant doped drain dye lasers effects elec electric field electrons emitter energy equation femtosecond flow flowmeter fluid flux frequency function GaAs gate glasses guideway HEMT holes hydrophone IEEE IGBT impedance increase layer linear liquid loop losses Maglev magnetic material measurement mechanical metal microwave mode molecules MOSFET noise nonlinear operating optical output p-n junction p-n-p transistor particles path phonon Phys physical piezoelectric pressure propagation properties pulse pump quency range ratio region resistance resonant result saturation semiconductor sensor shown in Fig signal silicon space structure substrate surface techniques temperature thermal threshold voltage tion topological space topology trans transducer transformer tunneling turbine turbulent typically ultrasonic vector velocity vibrational voltage wave wavelength York zero Zewail