1. A method for forming a metal/semiconductor/metal (MSM) back-to-back Schottky diode from a silicon (Si) semiconductor, comprising: providing a Si substrate; forming a bottom electrode with a Pt layer overlying the Si substrate, and a TiN layer overlying the Pt layer; forming an amorphous Si (a-Si) semiconductor layer overlying the bottom electrode, having a thickness in the range of 10 to 80 nanometers (nm); forming a TiN top electrode overlying the a-Si semiconductor layer; and, forming a MSM diode having a threshold voltage in the range of about 0.8 to 2 volts, and a breakdown voltage in the range of about 2.5 to 6 volts.