TY - JOUR
T1 - Mixed-size diamond seeding for low-thermal-barrier growth of CVD diamond onto GaN and AlN
AU - Smith, E.J.W.
AU - Piracha, A.H.
AU - Fields, D.
AU - Pomeroy, J.W.
AU - Mackenzie, G.R.
AU - Abdallah, Z.
AU - Massabuau, F. C-P.
AU - Hinz, A.M.
AU - Wallis, D.J.
AU - Oliver, R.A.
AU - Kuball, M.
AU - May, P.W.
PY - 2020/10/15
Y1 - 2020/10/15
N2 - We report a method of growing a diamond layer via chemical vapour deposition (CVD) utilizing a mixture of microdiamond and nanodiamond seeding to give a low effective thermal boundary resistance (TBR
eff) for heat-spreading applications in high-frequency, high-power electronic devices. CVD diamond was deposited onto thin layers of both GaN and AlN on Si substrates, comparing conventional nanodiamond seeding with a two-step process involving sequential seeding with microdiamond then nanodiamond. Thermal properties were determined using transient thermoreflectance (TTR), and the samples were also analysed with SEM and X-ray tomography. While diamond growth directly onto GaN proved to be unsuccessful due to poor adhesion, films grown on AlN were adherent and robust. The two-step mixed-seeding method gave TBR
eff values < 6 m
2 K GW
−1 that were 30 times smaller than for films grown under identical conditions but using nanodiamond seeding alone. Such remarkably low thermal barriers obtained with the mixed-seeding process offer a promising route for fabrication of high-power GaN HEMTs using diamond as a heat spreader with an AlN interlayer.
AB - We report a method of growing a diamond layer via chemical vapour deposition (CVD) utilizing a mixture of microdiamond and nanodiamond seeding to give a low effective thermal boundary resistance (TBR
eff) for heat-spreading applications in high-frequency, high-power electronic devices. CVD diamond was deposited onto thin layers of both GaN and AlN on Si substrates, comparing conventional nanodiamond seeding with a two-step process involving sequential seeding with microdiamond then nanodiamond. Thermal properties were determined using transient thermoreflectance (TTR), and the samples were also analysed with SEM and X-ray tomography. While diamond growth directly onto GaN proved to be unsuccessful due to poor adhesion, films grown on AlN were adherent and robust. The two-step mixed-seeding method gave TBR
eff values < 6 m
2 K GW
−1 that were 30 times smaller than for films grown under identical conditions but using nanodiamond seeding alone. Such remarkably low thermal barriers obtained with the mixed-seeding process offer a promising route for fabrication of high-power GaN HEMTs using diamond as a heat spreader with an AlN interlayer.
KW - chemical vapour deposition (CVD)
KW - thermal boundary resistance
KW - transient thermoreflectance (TTR)
KW - diamond seeding
UR - https://www.journals.elsevier.com/carbon
U2 - 10.1016/j.carbon.2020.05.050
DO - 10.1016/j.carbon.2020.05.050
M3 - Article
SN - 0008-6223
VL - 167
SP - 620
EP - 626
JO - Carbon
JF - Carbon
ER -