| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1997: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1996: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
The purpose of this work is to refine the device simulation model for ultra-small-sized semiconductor devices. We have tried to refine the energy transport model that can be used to treat the nonequilibrium carrier transport in nano-scale devices.
Heterojunction bipolar transistors (HBTs) are the semiconductor devices where the nonequilibrium carrier transport becomes particularly remarkable, and some analyzes by the energy transport model have been made. However, the methods of giving transport parameters were too rude. For an example, the composition- and doping-dependences of transport parameters were often neglected, and their energy dependence was not adequately incorporated. Therefore, in this work, we have developed a new method to give transport parameters (such as energy relaxation time, carrier mobility, and upper-valley fraction) for any composition, doping density and carrier energy. This is realized by using the Monte Carlo method and the linear extraporation method. This approach is applied to the simulation of AlGaAs/GaAs HBTs. As a result, we have found that the simplified conventional approaches lead to overestimation or underestimation of the velocity overshoot effects and to the inaccurate evaluation of the cutoff frequency characteristics, indicating the importance of giving adequate transport parameters. The method developed here can be easily applied to other devices that have position-dependent band structures.
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