Low temperature injected-caused charge carrier instability in n-type silicon below insulator-to-metal transition

A L Danilyuk,N I Kargin,S L Prischepa,I A Svito,A G Trafimenko,A K Fedotov

doi:10.1088/1361-648x/ab720e

Abstract

We report on the electric transport properties of Si heavily doped with Sb at concentration just below the insulator-to-metal transition in the temperature range 1.9–3.0 K for current density J < 0.2 A cm−2. The change in the sign of the temperature dependence of the differential resistivity was observed: the d/dT is positive if J < 0.045 A cm−2 whereas it becomes negative at J > 0.045 A cm−2. The effect is explained assuming the exchange by electrons between the upper Hubbard band (UHB) and the conduction band. The obtained J dependencies of the activation energy, nonequilibrium concentration, mobility and scattering time of the conduction electrons correspond well to this hypothesis. The reason for charge instability is the Coulomb repulsion between electrons occupying states both in the UHB and conduction band. The estimated J dependencies of the conduction electrons lifetime and concentration of the D− states in the UHB strongly supports this assumption.

Highlights

The physical mechanisms and effects associated with the manifestation of charge instability and an electronic Mott insulator-to-metal transition (IMT) in correlated electron systems are still the subject of intensive investigation [1,2,3]
The charge carrier instability induced by the applied current has been observed
By studying the current dependences of electrophysical param eters, such as differential resistance, activation energy, concentrations of conduction electrons and of D− states, electron mobility, scattering time, electron lifetime, we have shown that the resulting charge instability is due to delocalization of the electron states in the upper Hubbard band (UHB) caused by the Coulomb interaction with conduction electrons

Summary

Introduction

The physical mechanisms and effects associated with the manifestation of charge instability and an electronic Mott insulator-to-metal transition (IMT) in correlated electron systems are still the subject of intensive investigation [1,2,3]. In addition to the IMT itself, to study of the related effects These include, e.g. spin–orbit coupling induced by bismuth doping in silicon [11], variable-range hopping and Kondo effect signatures [12], conductivity and magnetoresistance near IMT [19], Coulomb gap in a doped semiconductor near IMT [20], spin relaxation near IMT and in hopping transport [21], hopping conductivity and IMT in doped semiconductor nanocrystal films [22, 23], emergence of metallic meta-stable phase [24] and metallic quantum fluctuations [17]. Those include, for example, reducing the power consumption when switching logic and memory elements, improving the param eters of MOSFET, increasing the selectivity of controlling qubits and the accuracy of electrical measurements of their state Some of these problems can be solved by using nonlinear effects in silicon, such as charge carrier instability, NDR and IMT [38]. Electrophysical parameters were estimated that has allowed to discuss mechanisms of charge carrier instability occurrence and change of a sign of temperature coefficient of differential resistivity (TCR) in the region preceding the NDR in Si:Sb below the IMT, i.e. on the insulating side of this transition

Experimental

Qualitative arguments

Findings

Quantitative analysis

Conclusions