1 2 Semiconductor and PN junction EEE 270

บทท 1 2 Semiconductor and P-N junction EEE 270 Electronic engineering

Semiconductor material Silicon wafer 2 EEE 270 Electronic engineering

Semiconductor material Silicon crystal Sand 25% silicon 3 EEE 270 Electronic engineering

Semiconductor material 4 EEE 270 Electronic engineering

Silicon atom 5 EEE 270 Electronic engineering

Intrinsic semiconductor Silicon Crystal at T= 0 °K 6 EEE 270 Electronic engineering

Energy gap 7 EEE 270 Electronic engineering

Energy level An electron-volt is the energy of an electron that has been accelerated through a potential difference of 1 volt, and 1 e. V= 1. 6*10 -19 joules 8 EEE 270 Electronic engineering

Intrinsic semiconductor Silicon Crystal at T > 0 °K 9 EEE 270 Electronic engineering

The Intrinsic Carrier Concentration ni B Eg T k 10 is the intrinsic carrier concentration is a constant related to the specific semiconductor material is the band-gap energy (e. V) is the temperature (°K) is Boltzmann’s constant (86 x 10 -6 e. V/°K) EEE 270 Electronic engineering

Electrical current 11 EEE 270 Electronic engineering

Doping and Extrinsic Semiconductors 12 EEE 270 Electronic engineering

N-type semiconductor 15 EEE 270 Electronic engineering

P-type semiconductor 16 EEE 270 Electronic engineering

Thermal equilibrium no = thermal equilibrium concentration of free electron po = thermal equilibrium concentration of hole Silicon Crystal at T > 0 °K 17 EEE 270 Electronic engineering

Thermal equilibrium (N-type) 18 EEE 270 Electronic engineering

Thermal equilibrium (P-type) 19 EEE 270 Electronic engineering

Drift and Diffusion Currents 20 EEE 270 Electronic engineering

Drift and Diffusion Currents 21 EEE 270 Electronic engineering

Drift and Diffusion Currents 22 EEE 270 Electronic engineering

Drift and Diffusion Currents 23 EEE 270 Electronic engineering

Drift and Diffusion Currents 24 EEE 270 Electronic engineering

Drift and Diffusion Currents 25 EEE 270 Electronic engineering

Drift and Diffusion Currents 26 EEE 270 Electronic engineering

Drift and Diffusion Currents 27 EEE 270 Electronic engineering

P-N junction Bell Labs the first transistor in December 1947. 28 EEE 270 Electronic engineering

P-N Junction 29 EEE 270 Electronic engineering

The Equilibrium P-N Junction 30 EEE 270 Electronic engineering

The Equilibrium P-N Junction Barrier potential or Built-in voltage is called thermal voltage, approximately 0. 026 V at room temperature, T=300 °K 31 EEE 270 Electronic engineering

Built-in voltage 32 EEE 270 Electronic engineering

P-N Junction biasing Forward-bias Non-bias Reward-bias 33 EEE 270 Electronic engineering

P-N Junction biasing 34 EEE 270 Electronic engineering

Junction capacitance 35 EEE 270 Electronic engineering

Reverse-Biased P-N Junction Reward-bias Cj : Junction Capacitance Cj 0 : Junction Capacitance at zero applied voltage VR : Reverse bias voltage Vbi : built-in voltage 36 EEE 270 Electronic engineering

Forward-Biased P-N Junction Forward-bias IS : Reverse-bias Saturation current, in the range of 10 -15 to 10 -13 VT : Thermal voltage n : emission coefficient or ideality factor, in the range 1 n 2 37 EEE 270 Electronic engineering

Forward-Biased P-N Junction 38 EEE 270 Electronic engineering