Thin-film transistors (TFTs) are the key building block of large-area electronics and can be found everywhere around us.
These are the very first set of TFTs on a 1mm glass substrate that I produced after joining my research group in Princeton. The black areas are the chromium transistor source/drain/gate contacts, whilst the brown area consists of the 150nm thick amorphous-silicon channel. The gate dielectric is not visible, being 300nm transparent silicon nitride.
I was so proud of my first devices built at Princeton that I posted this picture on Facebook. Within minutes I received my first comment -- from my younger sister, who said: "they really look like revisited space invaders!"