Silicon oxide (SiO 2 ) gate length, gate thickness, junction depth, and source/drain extension scaling have allowed metal–oxide–semiconductor (MOS) gate dimensions to approach the current ⩽100nm range. High dielectric constant materials for gate insulation and low resistivity junctions must be developed in order to enable further scaling of these devices. Aluminum oxide (Al 2 O 3 ), with a bandgap of 9.9eV, is an especially promising material for use as a gate insulator; however, conventional Al 2 O 3 processing techniques suffer from excessive thermal requirements. We have grown α-Al 2 O 3 thin films directly on silicon (100) at room temperature using pulsed laser deposition (PLD). Atomic-resolution transmission electron microscopy, Z-contrast scanning transmission electron microscopy, capacitance–voltage measurements, and current–voltage measurements were used to determine the nanoscale features and electrical properties of amorphous Al 2 O 3 thin films. Our results suggest that amorphous Al 2 O 3 films prepared using pulsed laser deposition may serve as high dielectric constant materials for next generation electronic devices.