Arduino based temperature controlled sample holder using a power transistor and its application to measure the band gap of a silicon p–n diode

Abstract

This experiment is developed with the aim of designing a temperature-controlled sample holder by using a commonly available power transistor as the heating element. Most temperature-controlled sample holders use commonplace heaters, which are made of high resistance materials like nichrome 80/20 (80% nickel, 20% chromium) wire and similar materials. The fabrication of this temperature-controlled sample holder also leads to the usage of high power electronic components, like power transistors and power resistors which are, otherwise, neglected in most laboratory experiments. Moreover, to develop this system, Arduino Uno Rev3 and resistance temperature detector (RTD) were used for the purposes of data acquisition and temperature measurement, respectively. Arduino is a single board micro-controller and RTD functions as a temperature sensor. This experiment serves as a good example of application and unification of basic concepts of electronics, heat and thermodynamics and offers an insight into data acquisition. The experiment is non-proprietary, and the apparatus is entirely made from off-the-shelf items. Thus, reconstruction and use will be simple and inexpensive. The power transistor, along with the power resistors, generates enough heat to raise the temperature of the sample holder by about 100 K. Also, to exhibit the working of the sample-holder, the energy band gap of the material of a p–n junction diode (silicon) has been determined experimentally using the setup.