Si‐SiO2‐Al capacitors were fabricated on both ⟨100⟩ and ⟨111⟩ oriented Si. The electron tunneling current from the Si accumulation layer was measured in the Fowler–Nordheim region. Comparing the current versus electric field for both crystal orientations, tunneling current is appreciably higher in ⟨100⟩ oriented than in ⟨111⟩ oriented capacitors. An explanation is suggested based on the conservation of transverse crystal momentum. The result implies that metal‐oxide‐semiconductor transistors fabricated on ⟨111⟩ oriented Si might be less susceptible to oxide injected charge instabilities than those fabricated on ⟨100⟩ oriented Si.