Photoconductive Response of a Quasi-One Dimensional Channel

摘要: Much of the physics quasi-one dimensional (ID) systems has been studied in so-called “ballistic channels” or “quantum point-contacts” defined by a negative voltage applied to two gates fraction micron wide and similar distance apart on top GaAs--(Ga,Al)As heterojunction containing electron gas (2DEG) (van Houten et al, 1990): channel length is much shorter than scattering lengths 2DEG, so transport through it ballistic. At B = 0 resistance quantized value h/2ie 2, where i number occupied ID subbands Wees al., 1988; Wharam 1988). interest focussed relationship between gate (Vg) electrostatic potential gates, which determines subband spacing channel. In studies, determined indirectly fitting theoretical predictions magnetic depopulation experimental data (Wharam 1989). An alternative approach use multiple quantum wire system, an array ~ 10,000 channels ~1 mm long fabricated (see e.g., Alsmeier 1989; Hansen 1987). Although large area off such samples means that transmission far-infrared (FIR) radiation can be used detect transitions states, also leads poorly properties, due toj averaging effects (Thornton 1986; Gao 1990). addition, spectra are complicated possible presence coupling wires (plasmons) (Batke 1985; 1986), non-local as depolarization shifts (Hansen 1986).