Amorphous silicon (aSi) voltage-controlled, variable capacitors (varactors) are utilized as rf amplitude modulators, such as for amplitude modulating the rf applied to an acoustic ink printhead. Large area fabrication processes are employed for vertically integrating these varactors with such printheads...http://www.google.com/patents/US4782350?utm_source=gb-gplus-sharePatent US4782350 - Amorphous silicon varactors as rf amplitude modulators and their application to acoustic ink printers
