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Defects induced by Metal-Semiconductor Contacts Formation
Published in Kazumi Wada, Stella W. Pang, Defects in Optoelectronic Materials, 2021
An ideal ohmic contact can flow current without any voltage drop through it, i.e., zero contact resistance. In optoelectronic devices, realization of low-resistance ohmic contacts is a critical issue for low-voltage as well as high-efficiency operation. If the contact resistance is high, for instance, in laser diodes, an actual applied voltage becomes large due to a voltage loss at the contacts, which might heat up the devices and hence degrade the device performance and reliability. In representative electronic devices with compound semiconductors, such as metal-semiconductor field effect transistor (MESFET) and high electron-mobility transistor (HEMT), source and drain contacts must be ohmic. If their contact resistance is high, a parasitic series resistance decreases the effective transconductance [128].
Contacting Systems
Published in Alan Owens, Semiconductor Radiation Detectors, 2019
All semiconductor devices generally need at least one ohmic contact; it is often the quality of this contact that significantly affects the performance of semiconductor devices. As discussed previously, the term ohmic refers in principle to a metal-semiconductor contact that (a) is non-injecting, (b) has a linear I-V characteristic in both directions and (c) has negligible contact resistance relative to the bulk or spreading resistance13 of the semiconductor. In practice, the contact is usually acceptable if it does not perturb the performance of the device substantially and can supply the required current density with a voltage drop that is small compared to the drop across the active region, implying that the contact resistance should be small. A small contact resistance is important for other reasons. For example, the RC time constant associated with the contact resistance may limit the frequency response of devices.
Deposition
Published in Sunipa Roy, Chandan Kumar Sarkar, MEMS and Nanotechnology for Gas Sensors, 2017
Sunipa Roy, Chandan Kumar Sarkar
An ohmic contact is defined as one in which there is an unrestricted flow of majority of the carriers from one material to another. It is mandatory to heavily dope the Si regions N+ or P+ so that an ohmic contact is ensured. The silicon doping level should be high enough (1019/cm3) to make a good ohmic contact. If the doping level is high enough, the depletion region width is low enough so that charge carriers can tunnel through the barrier. Barrier thickness is related to depletion by the depletion region width in the semiconductor (which is proportional to 1/ND). Aluminium is generally used to make an ohmic contact between metal and silicon.
SolCelSim: simulation of charge transport in solar cells developed in Comsol Application Builder
Published in International Journal of Modelling and Simulation, 2022
Joao A. T. P. Vieira, Peter Cendula
Ohmic contact represents a non-rectifying metal-semiconductor junction (no band bending) with the negligible resistance relative to the total resistance of the whole device. Ohmic contact is a non-selective contact which allows free electron and hole current with the negligible resistance. The electrostatic potential at the Ohmic contact is given by