Abstract
Two distinct components of tunneling current in silicon metal‐oxide‐semiconductor structures are identified. In addition to the electron tunneling from the conduction band of the semiconductor, there is a second component interpreted as electron tunneling from the valence band. This is manifested as hole current in the silicon substrate. The ratio of valence‐band to conduction‐band tunneling currents is about 103, and increases slightly with the oxide field. This ratio is independent of oxide thickness, temperature, and gate‐electrode material.