INP TUNNEL METAL-INSULATOR-SEMICONDUCTOR DEVICES IRRADIATED WITH 1-MEV ELECTRONS

Yb/p-InP and Au/n-InP tunnel metal-insulator-semiconductor (MIS) diodes were irradiated with 1 MeV electrons to a fluence of 1 x 10(15) e-/cm2. The forward current-voltage (I-V) and high-frequency capacitance-voltage (C-V) characteristics of electron-irradiated Yb/p-InP MIS diodes were measured over the temperature range 80-450 K. From the I-V/T data, the temperature dependence of the ideality factor n and the reverse saturation current I0 was determined. The temperature dependence of I0 fit very well to the thermionic emission model over the temperature range 250-450 K. The zero bias, zero temperature barrier height, phi(0) = 0.93 +/- 0.04 V, obtained from the above fitting procedure, agreed within experimental error with the value of phi(0) = 0.99 +/- 0.05 V, obtained from the C-V/T measurements. The interface-state density at the insulator-semiconductor interface of the irradiated Yb/p-InP tunnel diodes, deduced from the forward bias dependence of n at 309.1 K, was three times smaller than the one for the nonirradiated diodes. The deep-level transient spectroscopy studies in irradiated Yb/p-InP diodes indicated that the electron irradiation annealed an electron trap, introduced a new hole trap, shifted the other two original hole traps to slightly higher energies, increased their capture cross section by an order of magnitude, and reduced their concentration by about 50%. In Au/n-InP MIS diodes, electron irradiation annealed one electron trap and created a new electron trap, shifted the other two original electron traps to slightly lower energies, lowered the capture cross sections by an order of magnitude, and increased their concentrations by nearly 50%.