Effect of surface charge self-organization on gate-induced 2D electron and hole systems

Vitaly A Tkachenko,Oleg P Sushkov,Olga A Tkachenko,Dmitry G Baksheev

doi:10.3897/j.moem.6.3.63361

Vitaly A Tkachenko, Oleg P Sushkov + Show 2 more

Open Access

https://doi.org/10.3897/j.moem.6.3.63361

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Abstract

A simple model has been suggested for describing self-organization of localized charges and quantum scattering in undoped GaAs/AlGaAs structures with 2D electron or hole gas created by applying respective gate bias. It has been assumed that these metal / dielectric / undoped semiconductor structures exhibit predominant carrier scattering at localized surface charges which can be located at any point of the plane imitating the GaAs / dielectric interface. The suggested model considers all these surface charges and respective image charges in metallic gate as a closed thermostated system. Electrostatic self-organization in this system has been studied numerically for thermodynamic equilibrium states using the Metropolis algorithm over a wide temperature range. We show that at T &gt; 100 K a simple formula derived from the theory of single-component 2D plasma yields virtually the same behavior of structural factor at small wave numbers as the one given by the Metropolis algorithm. The scattering times of gate-induced carriers are described with formulas in which the structural factor characterizes frozen disorder in the system. The main contribution in these formulas is due to behavior of the structural factor at small wave numbers. Calculation using these formulas for the case of disorder corresponding to infinite T has yielded 2–3 times lower scattering times than experimentally obtained ones. We have found that the theory agrees with experiment at disorder freezing temperatures T ≈ 1000 K for 2D electron gas specimen and T ≈ 700 K for 2D hole gas specimen. These figures are the upper estimates of freezing temperature for test structures since the model ignores all the disorder factors except temperature.

Highlights

Charging of surface and interface defects is one of the key physical phenomena in semiconductor electronics [1,2,3,4]
The situation with a thin gate dielectric and shallow location of gate-induced systems is of interest for studying the role of surface charges [11, 12] and for the development of quantum systems with small characteristic lateral sizes [13]
The aim of this work is to briefly describe the simple model [14] that we suggested for illustrating the effect of Tkachenko VA et al.: Effect of surface charge self-organization electrostatic self-organization of surface charges on the gate-induced 2D electron or hole gas

Summary

Introduction

Charging of surface and interface defects is one of the key physical phenomena in semiconductor electronics [1,2,3,4]. A study of these structures containing gate-induced 2D quantum electron or hole systems has been initiated recently [5,6,7,8,9,10,11,12]. The situation with a thin gate dielectric and shallow location of gate-induced systems is of interest for studying the role of surface charges [11, 12] and for the development of quantum systems with small characteristic lateral sizes [13]. The aim of this work is to briefly describe the simple model [14] that we suggested for illustrating the effect of Tkachenko VA et al.: Effect of surface charge self-organization electrostatic self-organization of surface charges on the gate-induced 2D electron or hole gas

Test object and suggested model

Basic definitions and final formulas of the model

Metropolis algorithm calculations

Comparison: calculation vs experiment

Conclusions