CNR ExploRA

Articolo in rivista, 2023, ENG, 10.1016/j.mee.2023.112103

Structural and electrical correlation in aluminum nitride thin films grown by plasma enhanced atomic layer deposition as interface insulating layers on silicon carbide (4H-SiC)

Bruno Galizia a b, Patrick Fiorenza a, Corrado Bongiorno a, Béla Pécz c, Zsolt Fogarassy c, Emanuela Schilirò a, Filippo Giannazzo a, Fabrizio Roccaforte a, Raffaella Lo Nigro a

Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII n. 5 - Zona Industriale, 95121 Catania, Italy b Dipartimento di Scienze Chimiche, Università di Catania, INSTM, UdR Catania, Viale A. Doria 6, 95125 Catania, Italy c Centre for Energy Research, Institute of Technical Physics and Materials Science, Konkoly-Thege ut 29-33, 1121 Budapest, Hungary

(0001) oriented aluminum nitride (AlN) thin films have been grown by plasma enhanced atomic layer deposition (PE-ALD) on silicon carbide (4H-SiC) substrates. During different PE-ALD processes, the ammonia (NH3) plasma pulsing time has been varied and its effect on the microstructure and on the orientation degree of the AlN layers has been monitored. Structural characterization by Transmission Electron Microscopy (TEM) showed that the crystalline structure of the deposited films was strongly dependent on the NH3-plasma pulsing, so that different polymorphic structures were observed. In particular, both processes resulted in wurtzite AlN structure for few nanometers at the interface with the 4H-SiC substrate, while upon increasing thickness a poly-crystalline wurtzite phase was obtained by short-pulse NH3-plasma, whereas longer plasma exposure resulted in a mixture of wurtzite and zincblende defective phases. Phase formation mechanism were discussed and electrical nanoscopic characterization by conductive atomic force microscopy showed a clear correlation between the different AlN crystalline phases and the insulating properties.

Microelectronic engineering