Spatially resolved electrical properties of InAs/InP quantum dots and wires

Abstract

In this paper the electrical properties of InAs/InP nanostructures (wires and dots) were investigated using Kelvin probe electrostatic force microscopy and conductive atomic force microscopy techniques. Surface potential measurements were strongly affected by the presence of the thin InAs film at the top surface of the undoped InP buffer layer. These results and the electrical images suggest the suppression of the surface depletion region due to electron accumulation in InAs wires and dots. I–V spectroscopy shows the formation of a Schottky-type junction between the metal-coated Si tip and the semiconductor surface exposed to air. Larger conductances and different threshold voltages for current onset for the two types of nanostructure analysed here can be related to the particular electronic structure of InAs wires and dots.

Enhanced Surface Potential Variation on Nanoprotrusions of GaN Microbelt As a Probe for Humidity Sensing

“…Topography and SP images were acquired simultaneously using an Agilent 5500 with a three-lock-in amplifier in the amplitude modulation KPFM. , For the measurements, V AC bias at frequencies in the range 10−15 kHz plus a DC bias, V DC , were applied between tip and sample. The detector signal amplitude at the V AC frequency should be proportional to ( V DC − Δϕ) V AC ∂ C /∂ z , where C and z are the capacitance and distance between tip and sample, respectively . The SP images thus show the values of the DC bias that minimize this amplitude at each measured point.…”

“…The detector signal amplitude at the V AC frequency should be proportional to (V DC -Δφ)V AC ∂C/∂z, where C and z are the capacitance and distance between tip and sample, respectively. 8 The SP images thus show the values of the DC bias that minimize this amplitude at each measured point. These images show only SP variations along the image, since lock-in adjustments are made so that the initial SP value is close to zero.…”

Electrical properties of individual and small ensembles of InAs/InP nanostructures

“…3a for two dot diameters. For the wires, the threshold voltages (absolute values) are in the range 0.58-0.62 V [3], while for the wetting layer these values are larger, close to 1.1 V. Figure 3b and c show C-AFM images of a single wire extremity. The height difference between the two marked positions in the topographic image ( Fig.…”

“…Vertical transport measurements in semiconductor nanostructures -such as InAs/InP and InAs/GaAs quantum dots -have been investigated in literature mainly with Conductive Atomic Force Microscopy (C-AFM) [1][2][3]. The results provided electrical information about carrier transfer between a metalcoated tip and the nanostructure itself [4].…”

“…In this context, transport noise measurements have become an outstanding spectroscopy tool for nanostructure characterization, and have previously been applied to carrier trapping in impurities in Silicon MOS devices [5]. In particular, it is possible to study the influence of carrier localization phenomena on transport properties through nanostructures with different dimensionalities, using the InAs/InP system [3]. InAs self-assembles on InP in the form of nanowires and/or dots depending on the growth conditions [6,7].…”