Heterostructures Bipolar transistors 18 Semiconductors 17 Design and construction 13 Materials 11 Bipolar integrated circuits 8 Silicon 7 Electric properties 5 Epitaxy 5 Integrated circuits 5 Mathematical models 5 Optoelectronics 4 Characterization 2 Microelectronics 2 Nanostructured materials 2 Nanostructures 2 Low voltage integrated circuits 1 Silicium 1 Transistors 1 Very high speed integrated circuits 1