We have considered the basic pn Junction structure and discussed briefly how the space charge region is fonned. In this section we will examine the properties of the where no currents exist and no external excuitation step junction in thermal equilibrium. tion is applied. We will determine the space charge region width. electric fteld. and potential through the depletion region The analysts in this chapter is based on two asumptions that we have consid- ered in previous chapters. The first assumption is that the Boltzmann approximation s valid, which means that each semiconductor region is nondegenerately doped. The second assumption is that complete ionization exists. which means that the tempera. ture of the pn junction is not"too low.