I think that the "ripple" could be due to the way the circuit is built and how you are measuring it.
(A better word for the "ripple" would be "ringing". That is the usual expression for oscillation following a sharp change in a waveform).
You are running the circuit at quite a high frequency (100khz), which means that the ringing frequency will be several Mhz.
The circuit is built on a breadboard which itself is not good at high frequencies.
There are long wires connecting the various parts of the circuit, the long wires will have inductance.
The connection to the picoscope appears to be a simple twin wire cable rather than a low capacitance high impedance scope probe.
The twin cable will have significant amounts of capacitance, and inductance.
So, if you want perfect edges on your square waves, build the circuit on a low impedance ground plane with short connections, and make the measurements using a divider probe (divide by 10) for the scope.
JimB