A nanoscale pn junction in series with tunable Schottky barriers

Abstract

PN junctions in nanoscale materials are of interest for a range of technologies including photodetectors, solar cells and light-emitting diodes. However, Schottky barriers at the interface between metal contacts and the nanomaterial are often unavoidable. The effect of metalsemiconductor interfaces on the behavior of nanoscale diodes must be understood, both to extract the characteristics of the pn junction, and to understand the overall characteristics of the final device. Here, we study the current-voltage characteristics of diodes that are formed in fullysuspended carbon nanotubes. We utilize tunable Schottky barrier heights at the CNT-metal interface to elucidate the role of the Schottky barriers on the device characteristics. We develop a quantitative model to show how a variety of device characteristics can arise from apparently similar devices. Using our model we extract key parameters of the Schottky barriers and the pn junction, and predict the overall I-V characteristics of the device. Our equivalent circuit model is relevant to a variety of nanomaterial-based diode devices that are currently under investigation.

Extremely Efficient Photocurrent Generation in Carbon Nanotube Photodiodes Enabled by a Strong Axial Electric Field

“…Figure 1b shows the dark I−V sd characteristics of a CNT diode device. As reported previously, 16,24,25 we observe rectifying behavior in the reverse bias and an exponential turn-on in the forward bias with an ideality factor in the range of 1.05−1.32.…”

Growth of SiGeSn Thin Films Using Simplified PECVD Reactor towards NIR Sensor Devices

“…36 The Schottky junctions at the top and bottom led to the creation of an electrostatically coupled Schottky-diode-Schottky type of structure. 37 When a reverse bias is applied the p-n junction, the Schottky junctions are most likely switched into forward bias mode resulting in lowering of the Schottky barrier heights leading to large saturation currents. 38,39 When a forward bias is applied with respect to the p-n junction, the Schottky barrier heights increase resulting in the observed smaller current.…”

Lateral Photovoltaic Effect and Photo‐Induced Resistance Effect in Nanoscale Metal‐Semiconductor Systems

“…On the macroscopic perspective, when a bias voltage and a load resistor are used in series with the device, a voltage drop across the load resistors can be measured when the change in electrical conductivity of the material varies the current through the circuit . Classic examples of photoconductive effect include photoresistor and photodiode . Another phenomenon, photovoltaic effect, is more closely related to the photoelectric effect which utilizes the absorption of photo energy.…”