N-polar AlN nucleation layers grown by hot-wall MOCVD on SiC: Effects of substrate orientation on the polarity, surface morphology and crystal quality

• Hot-wall metalorganic vapor phase epitaxy enables a superior quality of group-III nitride epitaxial layers and high electron mobility transistor structures, but has not yet been explored for N-polar growth. In this work, we aim at achieving N-polar AlN nucleation layers (NLs) with optimized properties for subsequent growth of GaN device heterostructures. The effects of substrate orientation on the polarity, surface morphology and crystalline quality of AlN NLs on on-axis C-face SiC (000 (1) over bar), C-face SiC (000 (1) over bar) off-cut towards the [11 (2) over bar0] by 4 degrees, and Si-face SiC (0001) are investigated. The results are discussed in view of growth mode evolution with growth temperature and substrate orientation. It is demonstrated that N-polar AlN NLs with step-flow growth mode and 0002 rocking curve widths below 20 arcsec can be achieved on off-axis C-face SiC substrates.

Ämnesord

NATURVETENSKAP  -- Fysik -- Annan fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Other Physics Topics (hsv//eng)

Nyckelord

Hot-wall; AlN nucleation layer; Nitrogen-polar; Substrate orientation effect; MOCVD

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