Bipolar Junction Transistor

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Introduction

In this example we investigate a classical bipolar junction transistor which is one of the enablers of modern electronic devices.

Structure

The targeted structure is an NPN transistor depicted in figure q., with characteristics dopant concentrations in table 1.


	\input{/var/www/dokuwiki/data/media/physicswiki/bjt/transstr.tex}

Figure 1. Schematics of the BJT

	
	\begin{tabular}{ll}
		Base doping	& 5E23 $\frac{1}{m^3}$  \\
		Collector doping & 1E25 $\frac{1}{m^3}$\\
		Emmiter doping & 5E23 $\frac{1}{m^3}$
	\end{tabular}

Table 1. Parameters of the simulated BJT

Detailed description of the geometry with dimensions can be found in the project file online. \cite{bibid}.

Bandstructure


	\begin{tikzpicture}
		\node[inner sep=0pt] (russell) at (0,2)
		{\includegraphics[width=\textwidth]{/var/www/dokuwiki/data/media/physicswiki/bjt/CB.png}};
		\draw [|->] (0, -1) --(0, 4);
	\end{tikzpicture}

Figure 2. BJT conduction band

\
   \input{/var/www/dokuwiki/data/media/physicswiki/bjt/yslice.tex}

Figure 3. Conduction band profile y-axis slice

The band structure at zero bias is depicted in figure 2, and the slice in the y direction is plotted in figure 3. It shows the two pn-junctions, which middle 'base' region block the current flow from the emitter to the collector contact.

Voltage characteristics


   \input{/var/www/dokuwiki/data/media/physicswiki/bjt/besweep.tex}

Figure 4. Voltage characteristics
  • physicswiki/semiconductors/bjt.txt
  • Last modified: 2019/04/09 12:18
  • by zoltan.jehn