Figure 2.

Cross-sectional SEM images of curro pores etched into (100) n-type InP. aN_D = 1·10¹⁷ cm⁻³, U = 7 V, bN_D = 8·10¹⁷ cm⁻³, U = 5.5 V, cN_D = 3·10¹⁸ cm⁻³, U = 3 V. A magnified view of the pore tips is shown in the insets. In d, e, and f a typical FFT IS spectrum is shown in form of a Nyquist plot recorded after 38 min of etching. The points represent the measured data, the line is calculated by fitting the measurements to the model given in Eq. 1. The measurement frequencies are indicated