Okay kiddo, imagine you have a toy car that needs to go through a tunnel to get to the other side. But this isn't just any tunnel - it has a special shape that makes the car go really fast through it. That's sort of like what a resonant tunneling diode does.
A resonant tunneling diode is a tiny electronic device that helps electricity go through it really fast by using a special shape. Just like your toy car tunnel, this shape is designed to let electricity travel quickly through it.
The way it does this is by using a special layer in the middle of the device that's thinner than the other layers. This layer is like the perfect shape for electricity to zoom through really quickly without getting stuck. The electricity is able to pass through this layer and get to the other side really fast, like your toy car going through the special tunnel.
The resonant tunneling diode is a really important tool in electronic devices, because it helps make certain things work better. It's like having a shortcut that makes everything faster and smoother. And now you know how it works!