Semiconductor Physics Laboratory

Seminars and laboratory exercises will be conducted during the course, aiming at deepening the theoretical and experimental knowledge. The exercises will be divided into the following categories:

A. Introductory:
Learning how to operate instruments to be used in the experiments (multimeters, ammeters, voltmeters, oscilloscopes, signal generators, power supplies, etc.). Deepening knowledge in measurement theory, errors and error propagation. Instruments and circuits wiring and connection. Familiarization with semiconductor devices, good operation verification, and circuitry wiring rules. Safety rules and precautions.

B. Rectifying semiconductor devices:
Rectification and smoothing of alternating voltage using diodes and capacitors. In this exercise we will study the simple and double (full) rectification of an alternating voltage using commercially available components and observing the output waveform on an oscilloscope. Also, the use of capacitors to smoothen the output voltage will be examined.
Determination of electrical characteristics of semiconductor heterostructures by conductivity and Hall effect measurements in van der Pauw geometry samples. Conductivity, carrier concentration and mobility of the carriers, as well as the type of semiconductor (n or p), will be determined in appropriately prepared semiconductor van der Pauw geometry samples, by current-voltage measurements in the presence of magnetic field and without field.
Forward current, reverse bias current and depletion capacity in pn, pin and Schottky contacts. The carrier distribution in the above semiconductor heterostructures will be determined by capacitance versus voltage measurements.
Rectifying behavior and study of metal-semiconductor rectifying contacts at different temperatures. Determination of the semiconductor energy band gap. An analysis of the current mechanisms in pn or Schottky contacts will be carried out on new semiconductor materials, with current-voltage measurements at different temperatures.

C. Semiconductor optical devices:
Study of light emission from LEDs, as a function of the current and emission wavelength. The LED output will be studied as a function of the forward current, as well as the spectral analysis with the help of a monochromator, for different LED emission colors (red, green and blue).
Study of photodetectors constructed from photodiodes. The use of photodiodes for the construction of photodetectors will be studied, using reverse polarization of the photodiode and measuring the current with a pico-ammeter.

D. Transistor devices:
Determination of Junction Field Effect Transistor (JFET) operation characteristics. The operating characteristics will be determined by current-voltage measurements, under different bias conditions of the transistor, using voltage sources and appropriate circuitry.
Determination of Field Effect Transistor (MOSFET) operation characteristics. Transistor's transconductance, pinch-off voltage, and characteristic curves of the MOSFET will be determined as a function of gate voltage, In addition, the use of MOSFET as a switch will be examined.
Determination of Bipolar Transistor (BJT) operation characteristics. The emitter and collector characteristic curves will be determined and the current gain β will be calculated as a function of the collector current.