To evaluate the energy band gap of Silicon through the study of forward

bias characteristics

Trisha Banerjee _bhu @ 2010

Apparatus:-

(IN – 4007 ) Silicon diode, regulated 10 V dc power supply , 2 V range DVM ( digital volt meter) , fast temperature controlled oven, thermometer, milliamp range ammeter.

DVM

A circuit diagram associate with the experiment:-

Variable high resistance in series

pn junction diode

Milliammeter

Power supply

Trisha Banerjee _bhu @ 2010

Brief procedure about the experiment:-

1) initially we measure the diode current in forward bias at room temperature using the given diode kit.

2) secondly we measure the variation in voltage with the variation in temperature using the diode kit and the temperature controlling oven where the silicon diode is already dipped.

3) now using the particular slopes of the different characteristics graphs obtained by these variations we finally got the energy band gap of the diode dipped in oil bath.Trisha Banerjee _bhu @

2010

voltmeter

ammeter

High resistance in series

diodeKnob for adjusting the voltage

Trisha Banerjee _bhu @ 2010

DVM (Digital voltmeter) for measuring the voltage of the voltmeter

Trisha Banerjee _bhu @ 2010

Different graphs for determine the different slopesGraph for the slope of S1(i.e.forward characteristics of diode)

Graph for the slope S2 (i.e.. variation of voltage with temperature of diode).

Fast temperature controlling oven:-

Indicator for heat

Knob for ranging the temperature to heat

Thermometer for measure the temperature

Indicator for cooling

NOTES:-

1) initially totally switched off the oven , as the temperature initial increase the slow down of temperature is very difficult process as take much time.

2) get the forward bias characteristics with the variation of current with voltage in DVM.

3)now for the variation of voltage with temperature we have to very fast and accurate as for low temperature the variation is very fast and difficult to notice .

4) now for temperature detection the oven operating should be well known . For this experiment we set the ammeter to 2mAand switch off the diode kit . now raise the temperature about 5 points to the room temp . Till the cooling red light will be blow off and just when it reach the 5 points inc. temp the heat button glow then switched off the oven and then when the mercury stables note down the temperature and diode voltage from DVM at 2 mA constant current. Trisha Banerjee _bhu @ 2010