半导体材料与技术chapter4-3

1、Chapter 4 Semiconductor devices,4.1 Ideal pn junction 4.2 pn Junction Band Diagram 4.3 Bipolar Transistor 4.4 Junction Field Effect Transistor 4.5 Metal Oxide Semiconductor Field Effect Transistor 4.6 Light Emitting Diodes 4.7 Solar Cells,From Principles of electronic Materials Devices, SO Kasap (Mc

2、Graw-Hill, 2005),4.1 Ideal pn junction,4.1 Ideal pn junction,4.1 Ideal pn junction,4.1 Ideal pn junction,4.1 Ideal pn junction,4.1 Ideal pn junction,Considering an abrupt pn junction: net(x) can simply be described by step functions shown in Fig. (d). Using the step form of net(x) in Fig. (d) in the

3、 integration of gives the electric field at M.,Integrate the expression for E(x) in Fig. (e) to evaluate the potential V(x) and thus find V0 by putting in x=Wn.,W0=Wn+Wp, is the total width of the depletion region under a zero applied voltage.,The simplest way to relate V0 to the doping parameters i

4、s to make use of the fact that in the system consisting of p- and n- type semiconductors joined together, in equilibrium, Blotzmann statistics demands that the concentrations n1 and n2 of carriers at potential energies E1 and E2 are related by,Considering electrons (q=-e), we see from Fig. (g) that

5、E=0 on the p side far away from M where n=npo, and E=-eVo on the n-side away from M where n=nno. Thus,Which mean that Vo depends on nno and npo and hence on Nd and Na. The corresponding equation for hole concentrations is clearly,Rearranging And We obtain We can now write ppo and pno in terms of the

6、 dopant concentrations inasmuch as ppo=Na and,Forward bias: diffusion current,Forward bias: diffusion current,Forward bias: diffusion current,(b),Forward bias: diffusion current,(b),Forward bias: diffusion current,Law of the junction is an important equation that we,(b),Forward bias: diffusion curre

7、nt,(b),Forward bias: diffusion current,(b),Forward bias: diffusion current,(b),Forward bias: diffusion current,(b),Forward bias: diffusion current,Reverse biased pn junction. (a) Minority carrier profiles and the origin of the reverse current.,Reverse bias,Reverse biased pn junction. (a) Minority ca

8、rrier profiles and the origin of the reverse current.,Reverse bias,Reverse biased pn junction. (b) Hole PE across the junction under reverse bias,Reverse biased pn junction. (a) Minority carrier profiles and the origin of the reverse current.,Reverse bias,positive,Reverse biased pn junction. (a) Min

9、ority carrier profiles and the origin of the reverse current.,Reverse biased pn junction. (a) Minority carrier profiles and the origin of the reverse current.,Reverse biased pn junction. (a) Minority carrier profiles and the origin of the reverse current.,Reverse biased pn junction. (a) Minority car

10、rier profiles and the origin of the reverse current.,(a) Reverse I-V characteristics of a pn junction (the positive and negative current axes have different scales).,(a) Reverse I-V characteristics of a pn junction (the positive and negative current axes have different scales).,4.2 pn Junction Band

11、Diagram,4.2 pn Junction Band Diagram,4.2 pn Junction Band Diagram,4.2 pn Junction Band Diagram,4.2 pn Junction Band Diagram,4.2 pn Junction Band Diagram,Forward bias,Forward bias,Forward bias,Forward bias,Forward bias,Forward bias,Energy band diagrams for a pn junction under (c) reverse bias conditi

12、ons.,Reverse bias,Energy band diagrams for a pn junction under (c) reverse bias conditions.,Reverse bias,Reverse bias,Energy band diagrams for a pn junction under (d) Thermal generation of electron hole pairs in the depletion region results in a small reverse current.,Reverse bias,Energy band diagra

13、ms for a pn junction under (d) Thermal generation of electron hole pairs in the depletion region results in a small reverse current.,4.3 Bipolar Transistor,(a) A schematic illustration of the pnp bipolar transistor with three differently doped regions. (b) The pnp bipolar operated under normal and a

14、ctive conditions.,4.3 Bipolar Transistor,4.3 Bipolar Transistor,4.3 Bipolar Transistor,(c) The CB configuration with input and output circuits identified,(b) The pnp bipolar operated under normal and active conditions.,Fig. (c) shows the CB transistor circuit with the BJT represented by its circuit

15、symbol. The arrow identified the emitter junction and points in the direction of current flow when the EB junction is forward biased. Fig. (c) also identifies the emitter circuit, where VEB is connected, as the input circuit. The collector circuit, where VCB is connected, is the output circuit.,(c)

16、The CB configuration with input and output circuits identified,(b) The pnp bipolar operated under normal and active conditions.,(c) The CB configuration with input and output circuits identified,(b) The pnp bipolar operated under normal and active conditions.,(c) The CB configuration with input and

17、output circuits identified,(b) The pnp bipolar operated under normal and active conditions.,(c) The CB configuration with input and output circuits identified,(b) The pnp bipolar operated under normal and active conditions.,(c) The CB configuration with input and output circuits identified,(b) The p

18、np bipolar operated under normal and active conditions.,(c) The CB configuration with input and output circuits identified,(b) The pnp bipolar operated under normal and active conditions.,(c) The CB configuration with input and output circuits identified,(b) The pnp bipolar operated under normal and

19、 active conditions.,(c) The CB configuration with input and output circuits identified,(b) The pnp bipolar operated under normal and active conditions.,(c) The CB configuration with input and output circuits identified,(b) The pnp bipolar operated under normal and active conditions.,(c) The CB confi

20、guration with input and output circuits identified,(b) The pnp bipolar operated under normal and active conditions.,(c) The CB configuration with input and output circuits identified,(b) The pnp bipolar operated under normal and active conditions.,(c) The CB configuration with input and output circu

21、its identified,(b) The pnp bipolar operated under normal and active conditions.,(b) The pnp bipolar operated under normal and active conditions.,(d) The illustration of various current components under normal and active conditions.,(b) The pnp bipolar operated under normal and active conditions.,(d)

22、 The illustration of various current components under normal and active conditions.,(b) The pnp bipolar operated under normal and active conditions.,(d) The illustration of various current components under normal and active conditions.,In t, a,(b) The pnp bipolar operated under normal and active conditions.,(d) The illustration of various current components under normal and active conditions.,(b) The pnp bipolar operated under normal and active conditions.,(d) The illustration of various current components under normal and active conditions.,