Variable range hopping conductivity in molecular beam epitaxial InSb

• Published in: Journal of physics. D, Applied physics Vol. 55; no. 46; pp. 46 - 51
• Main Authors: Holmes, S N, Gough, J, Chen, C, Ritchie, D A, Pepper, M
• Format: Journal Article
• Language: English
• Published: IOP Publishing 17.11.2022
• Subjects: conductivity; hopping; InSb
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/1361-6463/ac941c

A variable range hopping (VRH) transport mechanism can be induced in molecular beam epitaxial, n-type doped InSb wafers with focussed Ga + ion beam damage. This technique allows areas of wafer to be selectively damaged and then subsequently processed into gated metal–insulator–semiconductor (MIS) devices where a disordered, two-dimensional (2D) device can be established. At high levels of damage (dose >10 16 Ga + ions cm −2 ) amorphous crystalline behavior results with activated conductivity characteristic of a three-dimensional system with VRH below 150 K. At lower doses (10 14 –10 16 Ga + ions cm −2 ) a thermally activated conductivity is induced at ∼0.9 K, characteristic of Mott phonon-assisted VRH. At 1 K the devices either conduct with conductivity >∼( e 2 / h ) where e is the fundamental charge and h is Planck’s constant, or are thermally activated depending on the dose level. The lightly damaged devices show weak antilocalization signals with conductivity characteristic of a 2D electronic system. As the Ga + dose increases, the measured phase coherence length reduces from ∼500 nm to ∼100 nm. This provides a region of VRH transport where phase-coherent transport processes can be studied in the hopping regime with the dimensionality controlled by a gate voltage in an MIS-device.