Short Base Pn Junction Diode Total Current Density Equation in steady state
Now consider when voltage \( V_D \) is applied to the diode. Consider the forward biased case and observe the following figure the linear profile will be explained in the next section Recall from previously due to minority carrier injection into the QNR(outside the depletion region) \( n_p(-x_p)\gg n_{po}(-x_{po})=n_{po} \) \( p_n(x_n)\gg p_{no}(x_{no})=p_{no} \) This is essentially the concentration difference that drives the net diffusion into the QNR. See below for more Boundary Conditions Note that at the ohmic contacts in this figure we ensure that \( p_n(W_n)=p_{no} \) \( n_p(-W_p)=n_{po} \) that is the minority carrier concentrations are at their thermal equilibrium concentrations. Essentially we are saying that all excess carries injected starting from the edge of SCR must all recombine at the ohmic contact after diffusing across the negative concentration gradient assuming the balance between the very large ...
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