Schottky barrier diodes fabricated on high-purity type-IIa CVD diamond substrates using an all-ion-implantation process

Abstract

We fabricated a Schottky barrier diode (SBD) on ion-implanted diamond substrates. The SBDs contained lightly doped regions under the Schottky electrodes and heavily doped regions beneath the Ohmic contacts. The current remained below 6.4 × 10−11 A at reverse biases of up to 10 V, but increased sharply at a forward bias of −3.5 V. The Schottky barrier height and ideality factor under forward bias were estimated to be 1.1 eV and 10, respectively. The hole concentrations obtained by measuring the capacitance at various supplied voltages were in good agreement with the values obtained from the Hall effect measurements.

The improvement of Schottky barrier diodes fabricated only by B ion implantation doping accomplished by refinement of the electrode structure

“…The Schottky barrier height is almost the same as that for previously reported diamond SBD with Al as the Schottky metal contact fabricated by the ion implantation technique. 26) Schottky barrier heights observed for SBD devices fabricated with Albased electrodes formed on CVD-boron-doped diamond film reported by Teraji et al were ranging from 1.01 to 1.28 eV. 32) Comparing the previous results obtained from implantationdoping, a significant difference is not observed in the barrier height value.…”

“…According to our previous report, the ideality factor was over than 10. 26) It is therefore suggested that the present device has significantly improved the electronic properties, though there are still some crucial points to improve SBD properties.…”

“…Although the reverse leakage current increased above 2 V, the rectification ratio increased by 14 times as the forward current increased owing to the decreased gap between the Schottky and Ohmic electrodes. 26) The parasitic series resistance decreased to 2.7 × 10 7 Ω.…”

“…Afterwards, Shigematsu et al reported on diamond SBD with Al as Schottky contacts in which the p-type channel was doped using the ion implantation technique. 26) They implanted B ions at RT with a B concentration of 5.0 × 10 18 cm −3 into the CVD diamond (001) substrate from the surface to a thickness of approximately 100 nm followed by post-annealing at 1150 °C. Al metal was used as the Schottky contact, and the distance between the Ohmic and Schottky contacts was 900 μm.…”

“…The parasitic resistance is approximately 10 times lower than the previously reported value although the Al Schottky contact is smaller. 26) This is likely because of the shortening of the distance between the Ohmic and Schottky contacts from 900 μm to 25 μm. The Schottky barrier height is almost the same as that for previously reported diamond SBD with Al as the Schottky metal contact fabricated by the ion implantation technique.…”