x = linspace(0,40);
Rp = 13 + 15; % in nm
sig = 5;

c = exp(-(x-Rp).^2/(2*sig^2));
plot(x,c);
grid off;
xlabel('Depth (nm)');
ylabel('Concentration (arb. units)');
title('Problem 1b: Implanting 30keV P into Si through 15nm-thick oxide.');