Luminescence study of polycrystalline CVD diamond films containing a smallamount of nitrogen

Polycrystalline diamond films were grown by the MPCVD method in a silica be ll-jar chamber on 2-in. silicon substrates. UV argon Laser (363.8 nm) -indu ced photoluminescence (PL) at liquid helium temperature and cathodoluminesc ence (CL) at liquid nitrogen temperature were performed on the films. For t he films containing varying amounts of nitrogen, PL spectra show a bright b lue/green luminescence and a broad band with sharp lines going from 550 to 650 nm attributed to nitrogen carbon vacancy (N-V) centers in different cha rge states. The intense blue/green contribution extends from 2.65 to 2.3 eV , with a sequence of sharp bands peaking at 2.6538, 2.5803, 2.5504, 2.4238 and 2.3652 eV. The average value of their separation is approximately 74 me V(similar to 600 cm(-1)). CL spectra show a prominent complex, broad band-A luminescence peaking at 2.72 eV, on which was superimposed the above blue/ green lines. Deep UV emissions were also obtained for energies greater than 3.0 eV, up to near the band edge, depending on the samples. (C) 2001 Elsev ier Science B.V. All rights reserved.