CNR ExploRA

Abstract in atti di convegno, 2016, ENG

Photoemission enhancement of nanodiamond particles by treatment in H2 or N2 plasmas

L. Velardi1, A. Valentini2, G. Cicala1

1P.LAS.M.I. Lab@CNR-NANOTEC, Via Amendola 122/D, 70126 Bari, Italy 2Dipartimento di Fisica, Università di Bari, Via Orabona 4, 70126 Bari, Italy.

Generally materials, having a low/negative electron affinity (NEA) and/or a low work function which facilitate the electron escape from their surfaces, exhibit good photo- and thermo-emission properties. From this point of view, natural and synthetic diamond is an interesting material because possesses a low EA that becomes negative when the surface is treated in H2 plasma. Moreover, as-grown diamond films produced by microwave plasma enhanced chemical vapour deposition and starting from CH4:H2 (1:99%) gas mixture exhibit hydrogenated surfaces, suitable for photocathodes, neutralizer cathode, energy converters and so on. Very recently the authors of this contribution have patented a new methodology (easy, inexpensive and working at temperature of 120°C) to fabricate layers of nanodiamond (ND) particles. In the present work, the photoemission behaviour of ND layers produced by this new methodology i.e. the pulsed spray technique is presented. Commercial (Diamonds & Tools srl) ND particles, 250 nm in size, were utilized. Layers of untreated and treated (in pure H2 or N2 plasmas) NDs were produced. The photoemission quantum efficiency (QE), a merit figure for photocathode applications, was assessed in the UV range (140-210 nm), showing a QE enhancement for both hydrogenated and nitrogenated ND particles.

V Workshop Plasmi, Sorgenti, Biofisica e Applicazioni, Lecce, 14-15 Ottobre 2016