A semiconductor detector of gravitational waves of a first frequency may include an oscillator having a metal coated oscillating member over a metal coated semiconductor substrate to be subjected to a Casimir attraction force towards the semiconductor substrate. The oscillator may be configured to exert a force to counterbalance the Casimir attraction force causing the oscillating member oscillates with a main harmonic resonance frequency equal to the first frequency. A displacement sensor may be coupled to the substrate and oscillating member and configured to sense oscillations and to generate corresponding sense signals. A pass-band filter may be tuned to the main harmonic resonance frequency and configured to generate band-pass replica signals of the sense signals, and an airtight package may be configured to keep a vacuum between the oscillating member and the semiconductor substrate. An array of semiconductor detectors and a method of detecting gravitational waves are also disclosed.