As an intermediate step for a Ph. D. degree, in Sweden there is a possibility of presenting a thesis. It should be seen as a step towards Ph. D., but also corresponds to a degree: Licentiate degree.
This thesis concerns modelling of Si/Si1-xGex Heterojunction Bipolar Transistors (HBT) and its applications. A physics-based large signal model including thermal dependence has been developed for Si/Si1-xGex HBTs. The alloying composition for the modelled device may vary between 0< x <0.30, having a pure silicon transistor as a special case. The model takes into account several effects that are important for the operation of Si/Si1-xGex HBTs and is directly related to the parameters in the fabrication process. Using extraction procedures for only a few parameters that inherently are difficult to predict, either due to uncertainties in the fabrication process or due to complex physical relations, a good agreement is found between the model and measurements. A new technique for extracting the thermal time constant of a device using small signal measurements is presented. The fitting procedure of electrical model parameters against measured data is described in the DC-case and particular effects are discussed. In the RF-case, effects from the variation of key equivalent circuit parameters on the different scattering parameters are discussed. With the model, a frequency doubler has been designed and fabricated. Measured results showed a conversion, from an input frequency of 27.5 GHz to an output frequency of 55 GHz, of -14 dB. Better results can be anticipated since the HBT in the fabricated circuit differed from the one used in the design. The agreement between simulated and measured data was good.
| compressed postscript (recommended): | uncompressed postscript |
| introduction (57 K) | introduction (163 K) |
| report (1.8 M) | report (18 M) |
| paper 1 (30 K) | paper 1 (135 K) |
| paper 2 (626 K) | paper 2 (2 M) |
| paper 3 (65 K) | paper 3 (342 K) |