Analytical description of mixed ohmic and space-charge-limited conduction in single-carrier devices

Abstract

While space-charge-limited current measurements are often used to characterize charge-transport in relatively intrinsic, low-mobility semiconductors, it is currently difficult to characterize lightly or heavily doped semiconductors with this method. By combining the theories describing ohmic and space-chargelimited conduction, we derive a general analytical approach to extract the charge-carrier density, the conduction-band edge and the drift components of the current density-voltage curves of a single-carrier device when the semiconductor is either undoped, lightly doped or heavily doped. The presented model covers the entire voltage range, i.e., both the low-voltage regime and the Mott-Gurney regime. We demonstrate that there is an upper limit to how doped a device must be before the current density-voltage curves are significantly affected, and we show that the background charge-carrier density must be considered to accurately model the drift component in the low-voltage regime, regardless of whether the device is doped or not. We expect that the final analytical expressions presented herein to be directly useful to experimentalists studying charge transport in novel materials and devices.

The Origin of Low Contact Resistance in Monolayer Organic Field‐Effect Transistors with van der Waals Electrodes

“…Specifically, in organic semiconductors with relatively low mobility while comparing with the inorganic one, the current travelling through the contact has shown to be linear proportion to the bulk mobility. [ 30–33 ] The R I value is given by , where A inj is the charge injection area.…”

Fast-Response Flexible Temperature Sensors with Atomically Thin Molybdenum Disulfide

“…We analyze the conduction mechanism of sensors after encapsulation and deduce that space-charge limited current is present, a common mechanism in lightly doped semiconductors (see Section S9 in the Supporting Information and Figure S5). 31 We also find there are growth-to-growth variations affecting the nonlinearity of the current−voltage characteristics and E A , indicating differences in doping density: e.g., from variations in sulfur vacancy concentrations (Figure S6). 31,32 We further investigate the response time of our flexible MoS 2 temperature sensors by fabricating thin metal microheaters (Ti/Pd 3/37 nm) on top of the Al 2 O 3 passivation layer (Figure 3a−c).…”

“…31 We also find there are growth-to-growth variations affecting the nonlinearity of the current−voltage characteristics and E A , indicating differences in doping density: e.g., from variations in sulfur vacancy concentrations (Figure S6). 31,32 We further investigate the response time of our flexible MoS 2 temperature sensors by fabricating thin metal microheaters (Ti/Pd 3/37 nm) on top of the Al 2 O 3 passivation layer (Figure 3a−c). We apply a negative voltage pulse with an amplitude of V p = −1.5 V, a period of 1 ms, and a 50% duty cycle to the heater while the sensor is direct-current biased with the voltage V = 2 V. We apply a negative V p to avoid accidentally "turning on" the MoS 2 sensor under the metal heater, because such CVD-grown MoS 2 devices are n-type and in a transistor configuration they turn on with positive gate voltages.…”

In Situ Visualization and Quantification of Electrical Self‐Heating in Conjugated Polymer Diodes Using Raman Spectroscopy

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