Gate Oxide Electrical Stability of p-type Diamond MOS Capacitors

This paper shows the effect of performing consecutive measurement prior to negative bias stress instability (NBSI) on diamond metal-oxide-semiconductor capacitor (MOSCAP). For the first time, time-dependent stress tests have been carried out in order to investigate the stability of the flatband voltage (VFB) of MOSCAPs through capacitance-voltage (CV) measurements. Two tests have been performed. In the first test, consecutive CV measurements with the device biased from deep depletion to the accumulation regime were performed to monitor the recovery of the VFB. In the second test, NBSI technique has been applied. VFBstability has been measured by means of a time-dependent bias stress in which the device was polarized at a fixed negative voltage for a specific time interval prior to performing the next CV measurement. As VFBis directly connected to the effective oxide charge (Neff), the two different tests allowed the extraction of total amount of Neffthat interfered during the measurements. The result observed shows that the postoxidation annealing process induces a strong enhancement of the MOSCAP stability together with a decrease of Neff.