Investigated nanocrystalline (grain size < 100 nm) submicron thick GaN, AlN and BN layers were produced on Si substrates by means of reactive crystallization from impulse plasma (RPP CVD method), while diamond-like carbon (DLC) films were obtained in the course of radio frequency (13.56 MHz) chemical vapor deposition (RF CVD) process. In our previous works (e.g. [1-3]) we presented results of the studies of their optical (refractive index value, absorption edge value), electronic (resistivity, dielectric constant, state of the substrate/layer interface) as well as low-temperature photoluminescent properties . Attempts of correlating structural, optical and electronic properties of discussed films with their photoluminescent characteristics were also undertaken.
In the present study we investigated photoluminescence (PL) of the layers excited by He-Cd laser (325 nm) beam at the room temperature. All materials, except BN, demonstrated PL in UV and violet light (fairly homogenous in plane in the case of GaN and AlN). Relatively the most intensive emission was observed for DLC and AlN films. Moreover, the subject of investigations was also cathodoluminescence (CL) of GaN and AlN layers. Both showed very broad-band emission, fairly homogenous in plane. An attempt of correlating luminescent properties of studied materials at room temperature with their bandgap widths and nanocrystallinity is presented as well.
 A.Werbowy, J.Szmidt, A.Sokolowska, A.Olszyna, Diamond Relat. Mater., 9(1998)609.
 A.Werbowy, J.Szmidt, A.Sokolowska, Ceramics: Getting into the 2000s - Part E, P.Vincenzini (ed.), Faenza, 1999, p.85.
 A.Werbowy, P.Firek, J.Szmidt, A.Olszyna, M.Galazka, J. Wide Bandgap Mater., 9(2002)169.
 J.Siwiec, A.Sokolowska, A.Olszyna, R.Dwilinski, M.Kaminska, J.Konwerska-Hrabowska, NanoStructured Mater., 10(1998)625.