Diffusion thermopower of a 2DEG

Abstract

We investigate the effect of the b d g r w n d impurity concentration Ne1on the thermopower of a GsAs/AIGaAs hetemjunction. A comparison between a GeAs/AIGaAs hetemjunction and a Si MOSFET is also given. For the hetemjunction we alwaye find a negative sign for the thempower, in contrast to the Si MOSFET for which the sign sometimes changes with inmming NBI. This different behaviour is due to the difference of the confining potentials cI the two system.

Diffusion thermopower of a p‐type Si/Si1–xGex heterostructure at zero magnetic field

“…In fact, the roughness amplitude 1 3 ∆ = . Å is small comparing to those normally used [2][3][4][5][6], thus it is necessary to propose an interpretation for this value. It has been pointed out [17,18] that a strained layer, as thinner than a critical thickness [25], prefer to relax by buckling which gives raise interface roughness.…”

“…The background impurity scattering examined in some previous studies [2,3] is not considered here. The reason is that our HS has only an impurity sheet separated from the well by a spacer of thickness S 120 L = Å, but no intentional background impurity [1,11].…”

“…At very low temperature, the total thermopower S , approximated by the diffusion thermopower d S , was explained by a phenomenological model without calculations starting from the microscopic level [1]. Since many theoretical studies [2,3] of the diffusion thermopower are available, it may be interesting if one can use them to examine the reported data.…”

“…Among the scatterings determining diffusion thermopower, impurity doping and interface roughness are normally studied [2,3]. However, proper considerations for diffusion thermopower due to deformation potential and alloy disorder, to the best of our knowledge, are unavailable.…”

“…Further, some assumptions used in the existing studies are actually weak. First, the potential barrier at the HS's interface is always assumed to be infinite [2,3], although it is small, thus changes the transport properties of the HS [3,4]. Next, deformation potential scattering limiting the 2D hole mobility is always based on the idea that the holes and the electrons undergo the same deformation potential [5].…”