Growth-temperature optimization for low-carrier-density $In0.75Ga0.25As$-based high electron mobility transistors on InP Available to Purchase

Two-dimensional electron gases (2DEGs) were formed in undoped $In0.75Al0.25As∕In0.75Ga0.25As∕In0.75Al0.25As$ quantum wells. The optimal growth temperature for this structure is $410°C$⁠, with peak 2DEG electron mobility and density values of $μ=221000cm2∕Vs$ and $n=1.36×1011cm−2$ at $1.5K$⁠. This electron mobility is equal to the highest previously published for these undoped structures but with a factor of 2 reduction in $n$⁠. This has been achieved through the use of a significantly thinner InAlAs graded buffer, which supports the theory that this is the source of the 2DEG electrons. For $n>1.6×1011cm−2$⁠, $μ$ is shown to be 10% higher for transport parallel to the [011] crystal axis. This is a direct result of anisotropic surface morphology.