Thermal conductivity of amorphous thin-film Al–P–O on silicon

• The thermal conductivity of amorphous AlPO films is less than 1 W m −1 K −1.
• Films annealed at 450 °C and 600 °C have the same thermal conductivity.
• The thermal conductivity of bulk silicon depends on the dopant concentration.

The thermal conductivity, measured by the 3ω method, of amorphous films of Al2P1.2O6 (AlPO) deposited on Si substrates by an all-aqueous spin-coating technique is 0.93(3) W m− 1 K− 1. The thermal conductivity of a degenerately doped n-Si substrate is 85(5) W m− 1 K− 1 and of a more lightly doped p-Si substrate is 139(7) W m− 1 K− 1. The AlPO thermal conductivity is independent of film thickness in the range 45–200 nm. The total thermal resistance is dominated by the film contribution for film thicknesses above 50 nm, and for smaller thicknesses, interface contributions become significant.