Browsing by Author "Zhao, Ming"

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The Influence of AlN Nucleation Layer on Radio Frequency Transmission Loss of AlN-on-Si Heterostructure
(1970-01-01)
Chang, Shane
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Zhao, Ming
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Spampinato, Valentina
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Franquet, Alexis
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Thi-Hien Do
Reducing radio frequency (RF) transmission loss is a key requirement when fabricating GaN-on-Si RF devices. To get a better insight into the RF loss mechanism in the GaN-on-Si structure, the RF loss of an AlN/Si template is investigated by varying the growth temperature of AlN during a metalorganic chemical vapor deposition process. The results show that the RF loss of the AlN/Si template is dominated by the interface loss due to the p-type conductive channel at the AlN/Si interface, which is induced by the thermal diffusion of Al during the high-temperature growth. Although a low growth temperature of the AlN nucleation layer can suppress the RF loss in the AlN/Si template, it results in a low crystalline quality of AlN for practical use. Optimizing the growth temperature of the AlN nucleation layer is essential to obtain a good balance between the crystalline quality, morphological quality, and RF loss such that the AlN/Si template is suitable for epitaxial growth of the complete GaN-on-Si RF device structure.
The influence of AlN nucleation layer on RF transmission loss of GaN buffer on high resistivity Si (111) substrate
(2020-03-01)
Chang, Shane
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Zhao, Ming
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Spampinato, Valentina
;
Franquet, Alexis
;
Chang, Li
A sufficiently low transmission loss in radio frequency (RF) is one of the critical requirements for GaN-on-Si RF devices to achieve high performance. We have systematically studied the mechanism and effect of the AlN nucleation layer on the RF loss of the GaN-on-Si device buffer stack. Our results show that the RF loss is strongly influenced by the growth parameters of the AlN nucleation layer during epitaxial process. It is observed that the AlN nucleation layer grown at a low thermal budget with a low density of deep surface pits can efficiently reduce the AlN/Si interface loss by suppressing the conductive channel at AlN/Si interface which is governed largely by the thermal diffusion of Al and Ga into the Si substrate. By optimizing the growth process of the AlN nucleation layer, the RF loss of the GaN-on-Si device buffer can be dramatically reduced by up to similar to 40%.