One type of these devices is called n-channel or p-channel based on gate voltage. Bootstrap circuits can be used to reduce the saturation voltage due to use of the bipolar junction types of these devices. These devices, which were first created at Bell Labs using gold foil contacts on a piece of germanium, went on to replace the vacuum tube in electronic circuits. The density of these objects in an integrated circuit tends to double every two years or so, according to Moore's law. For 10 points, name these semiconductor circuit elements that serve as switches and amplifiers, often made of silicon.
a) Diodes
b) Transistors
c) Capacitors
d) Resistors