Learn More About QuestEDS

QuestEDS is an important benefit of being an EDS member.  Are you interested in knowing why it's not possible to measure the built-in voltage of a PN junction using a voltmeter? Do you need to understand the best way to derive an expression for the average thermal velocity of an electron? Or are you curious about what quantum dots and wires are? The answers to these questions and more are available through QuestEDS.

Below is a sample of what you can expect to find in the QuestEDS Library.  Want to see more, join EDS today!

Question: What methodology can be used for quantum approach to transport in nano devices which utilizes the minimum computation time?

Answer: The specific method chosen depends on the problem being addressed. Among the many methods for quantum transport, one method has been broadly accepted; the so-called non-equilibrium Green's function (NEGF) method. This method has a firm basis in theory and has been successfully applied to problems from quantum transport in molecules, carbon nanotubes, semiconductor nanowires, nanoscale MOSFETs, spintronic devices, and more. For an introduction to the approach, visit www.nanoHUB.org, search "Datta" and look for the series of four lectures, "Concepts in Quantum Transport."

For simple nanodevices such as carbon nanotubes, the NEGF approach is often quite efficient, but for nanoscale MOSFETs, for example, the computational burden can be very large. (The NEGF approach is equivalent to solving the Boltzmann Transport Equation with one additional dimension.) For nanoscale MOSFETs, the so-called "density-gradient" or "effective potential" approach is often used. This method can be implemented by an added term to the drift-diffusion equation, and it can be used to "include" quantum transport" in Monte Carlo simulation. It is much more efficient than NEGF simulation, but needs to be carefully used and benchmarked against more rigorous methods such as NEGF.