| Title |
Overshoot mechanism in transient excitation of THz and Gunn oscillations in wide-bandgap semiconductors
|
|---|---|
| Published in |
Discover Nano, November 2012
|
| DOI | 10.1186/1556-276x-7-647 |
| Pubmed ID | |
| Authors |
Ernesto Momox, Nick Zakhleniuk, Naci Balkan |
| Abstract |
A detailed study of high-field transient and direct-current (DC) transport in GaN-based Gunn diode oscillators is carried out using the commercial simulator Sentaurus Device. Applicability of drift-diffusion (DD) and hydrodynamic (HD) models to high-speed, high-frequency devices is discussed in depth, and the results of the simulations from these models are compared. It is shown, for a highly homogeneous device based on a short (2 μm) supercritically doped (1017 cm-3) GaN specimen, that the DD model is unable to correctly take into account some essential physical effects which determine the operation mode of the device. At the same time, the HD model is ideally suited to solve such problems due to its ability to incorporate non-local effects. We show that the velocity overshoot near the device contacts and space charge injection and extraction play a crucial role in defining the operation mode of highly homogeneous short diodes in both the transient regime and the voltage-controlled oscillation regime. The transient conduction current responses are fundamentally different in the DD and HD models. The DD current simply repeats the velocity-field (v-F) characteristics, and the sample remains in a completely homogeneous state. In the HD model, the transient current pulse with a full width at half maximum of approximately 0.2 ps is increased about twofold due to the carrier injection (extraction) into (from) the active region and the velocity overshoot. The electron gas is characterized by highly inhomogeneous distributions of the carrier density, the electric field and the electron temperature. The simulation of the DC steady states of the diodes also shows very different results for the two models. The HD model shows the trapped stable anodic domain in the device, while the DD model completely retains all features of the v-F characteristics in a homogeneous gas. Simulation of the voltage-controlled oscillator shows that it operates in the accumulation layer mode generating microwave signals at 0.3 to 0.7 THz. In spite of the fact that the known criterion of a Gunn domain mode n0L > (n0L)0 was satisfied, no Gunn domains were observed. The explanation of this phenomenon is given. |
Mendeley readers
The data shown below were compiled from readership statistics for 8 Mendeley readers of this research output. Click here to see the associated Mendeley record.
Geographical breakdown
| Country | Count | As % |
|---|---|---|
| Unknown | 8 | 100% |
Demographic breakdown
| Readers by professional status | Count | As % |
|---|---|---|
| Student > Ph. D. Student | 3 | 38% |
| Professor | 1 | 13% |
| Student > Bachelor | 1 | 13% |
| Researcher | 1 | 13% |
| Professor > Associate Professor | 1 | 13% |
| Other | 0 | 0% |
| Unknown | 1 | 13% |
| Readers by discipline | Count | As % |
|---|---|---|
| Engineering | 4 | 50% |
| Physics and Astronomy | 2 | 25% |
| Sports and Recreations | 1 | 13% |
| Unknown | 1 | 13% |
Attention Score in Context
This research output has an Altmetric Attention Score of 1. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 24 November 2012.
All research outputs
#22,760,732
of 25,374,917 outputs
Outputs from Discover Nano
#798
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Outputs of similar age
#255,304
of 285,320 outputs
Outputs of similar age from Discover Nano
#15
of 95 outputs
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