294385.fig.004a
(a)
294385.fig.004b
(b)
294385.fig.004c
(c)
294385.fig.004d
(d)
Figure 4: AFM images of 3D surface morphology of bulk and porous GaAs with the variation of DMF concentration in the mixture of H2SO4 acid for (a) bulk, (b) sample D, (c) sample E, and (d) sample F, at current density, = ~250 mA/cm2, and time,  min.