Static and transient electrical properties of (111) diamond p–n diodes

Electrical properties of diamond p–n diodes grown on (111) diamond substrate and processed by reactive ion etching are investigated. The diodes comprise a metallic ohmic contact on the top of a stack n + /n/p/p + /(111)C grown on a monocrystalline diamond substrate and an other ohmic contact on the p + layer. Boron and phosphorus concentrations are measured by SIMS, the p and n ones being respectively 7 × 10 17 and 1 × 10 18 cm –3 , and compared to the capacitance–voltage response of the diodes, showing an almost complete activation of dopants. Current–voltage I ( V ) characteristics are measured from ambient temperature up to 872 K. Rectifying factors at ±10 V are close to seven orders of magnitude at ambient temperature, and still above four between 800 K and 872 K. Capacitance detected deep level transient spectroscopy (C‐DLTS) is performed between 400 and 850 K in order to track impurities and defect centres. No majority carrier traps are detected. DLTS spectra appear only when an injection pulse is applied, indicating the presence of minority carrier traps, with concentrations only in the 10 15 cm –3 range. Both standard and multi‐exponential transients analysis are performed to extract ionisation energies and capture cross sections. DLTS spectra performed repetitively show unambiguous evolutions after thermal cycling, evidenced by modifications undergone by deep levels appearing at the highest temperatures. These changes are induced by the simultaneous presence of electric field and heating while change does occur neither for deep levels appearing at the lowest temperatures nor for I ( V ) characteristics. Comparison of these data in two diodes suggests that deepest levels have a bulk origin whereas shallower ones are surface‐related, possibly due to the reactive ion etching process. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)