Electrical properties of atomic layer deposited HfO2/Al2O3 multilayer on diamond

• A HfO2/Al2O3 multilayer has been deposited by ALD technique on diamond.
• The k value for HfO2/Al2O3 multilayer is larger than that for single ALD-Al2O3.
• Fixed charge density of HfO2/Al2O3/H-diamond is lower than that of HfO2/H-diamond.
• The ALD-HfO2/Al2O3/H-diamond MISFET shows good electrical properties.

A HfO2/Al2O3 multilayer has been deposited by an atomic layer deposition (ALD) technique on a hydrogenated-diamond (H-diamond) epitaxial layer. Electrical properties of the ALD-HfO2/Al2O3/H-diamond metal-insulator-semiconductor (MIS) diode have been investigated to compare with those of the single ALD-Al2O3/H-diamond and ALD-HfO2/H-diamond MIS diodes. The leakage current density for the ALD-HfO2/Al2O3/H-diamond MIS diode is smaller than 3.8 × 10− 8 A·cm− 2 with electric field ranging from − 1.6 to 1.0 MV·cm− 1. The dielectric constant for the ALD-HfO2/Al2O3 multilayer is larger than that for the single ALD-Al2O3. The fixed charge density in the ALD-HfO2/Al2O3/H-diamond structure is much lower than that in the single ALD-HfO2/H-diamond structure. The electrical properties of the ALD-HfO2/Al2O3/H-diamond MIS field effect transistor have also been investigated. The source–drain current and extrinsic transconductance maxima are − 42.1 mA·mm− 1 and 6.2 ± 0.1 mS·mm− 1, respectively. The effective mobility for the H-diamond channel layer has been determined to be 38.2 ± 0.5 cm2·V− 1·s− 1.