Thickness Dependent Parasitic Channel Formation at AlN/Si Interfaces.
Sci Rep. 2017 Nov 16;7(1):15749
Authors: Chandrasekar H, Bhat KN, Rangarajan M, Raghavan S, Bhat N
The performance of GaN-on-Silicon electronic devices is severely degraded by the presence of a parasitic conduction pathway at the nitride-substrate interface which contributes to switching losses and lower breakdown voltages. The physical nature of such a parasitic channel and its properties are however, not well understood. We report on a pronounced thickness dependence of the parasitic channel formation at AlN/Si interfaces due to increased surface acceptor densities at the interface in silicon. The origin of these surface acceptors is analyzed using secondary ion mass spectroscopy measurements and traced to thermal acceptor formation due to Si-O-N complexes. Low-temperature (5 K) magneto-resistance (MR) data reveals a transition from positive to negative MR with increasing AlN film thickness indicating the presence of an inversion layer of electrons which also contributes to parasitic channel formation but whose contribution is secondary at room temperatures.
PMID: 29146979 [PubMed - in process]
Dynamic infrared thermography (DIRT) for assessment of skin blood perfusion in cranioplasty: a proof of concept for qualitative comparison with the standard indocyanine green video angiography (ICGA).
Int J Comput Assist Radiol Surg. 2017 Nov 15;:
Authors: Rathmann P, Chalopin C, Halama D, Giri P, Meixensberger J, Lindner D
PURPOSE: Complications in wound healing after neurosurgical operations occur often due to scarred dehiscence with skin blood perfusion disturbance. The standard imaging method for intraoperative skin perfusion assessment is the invasive indocyanine green video angiography (ICGA). The noninvasive dynamic infrared thermography (DIRT) is a promising alternative modality that was evaluated by comparison with ICGA.
METHODS: The study was carried out in two parts: (1) investigation of technical conditions for intraoperative use of DIRT for its comparison with ICGA, and (2) visual and quantitative comparison of both modalities in a proof of concept on nine patients. Time-temperature curves in DIRT and time-intensity curves in ICGA for defined regions of interest were analyzed. New perfusion parameters were defined in DIRT and compared with the usual perfusion parameters in ICGA.
RESULTS: The visual observation of the image data in DIRT and ICGA showed that operation material, anatomical structures and skin perfusion are represented similarly in both modalities. Although the analysis of the curves and perfusion parameter values showed differences between patients, no complications were observed clinically. These differences were represented in DIRT and ICGA equivalently.
CONCLUSIONS: DIRT has shown a great potential for intraoperative use, with several advantages over ICGA. The technique is passive, contactless and noninvasive. The practicability of the intraoperative recording of the same operation field section with ICGA and DIRT has been demonstrated. The promising results of this proof of concept provide a basis for a trial with a larger number of patients.
PMID: 29143240 [PubMed - as supplied by publisher]