Nitride Semiconductors

Dadgar, A.; Weyers, M.

doi:10.1002/9781119313021.ch4

Cited by 3 publications

(2 citation statements)

References 203 publications

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“…Accordingly, Czochralski (CZ)-type HR-Si(111) substrates (specified resistivity ≥3 kΩ cm) were chosen for the study. Note that float-zone (FZ) HR wafers were intentionally avoided given their higher cost and propensity to plastic deformation (such as slip) at MOVPE process temperatures. , Prior to growth, noncontact RF eddy current induction-based evaluation confirmed that sheet resistances ( R SH ) of all of the eight wafers were higher than the limit of the measurement system (∼10 kΩ/□). On six of these, a nominally 250 nm thick AlN nucleation layer was grown by MOVPE under conditions typical of our standard HEMT structures. ,, In detail, this AlN layer growth is divided into four steps, which are successively performed in the reactor.…”

Section: Resultsmentioning

confidence: 99%

Origin(s) of Anomalous Substrate Conduction in MOVPE-Grown GaN HEMTs on Highly Resistive Silicon

Ghosh

Hinz

Fairclough

et al. 2021

ACS Appl. Electron. Mater.

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The performance of transistors designed specifically for high-frequency applications is critically reliant upon the semiinsulating electrical properties of the substrate. The suspected formation of a conductive path for radio frequency (RF) signals in the highly resistive (HR) silicon substrate itself has been long held responsible for the suboptimal efficiency of as-grown GaN high electron mobility transistors (HEMTs) at higher operating frequencies. Here, we reveal that not one but two discrete channels distinguishable by their carrier type, spatial extent, and origin within the metal-organic vapor phase epitaxy (MOVPE) growth process participate in such parasitic substrate conduction. An ntype layer that forms first is uniformly distributed in the substrate, and it has a purely thermal origin. Alongside this, a p-type layer is localized on the substrate side of the AlN/Si interface and is induced by diffusion of group-III element of the metal-organic precursor. Fortunately, maintaining the sheet resistance of this p-type layer to high values (∼2000 Ω/□) seems feasible with particular durations of either organometallic precursor or ammonia gas predose of the Si surface, i.e., the intentional introduction of one chemical precursor just before nucleation. It is proposed that the mechanism behind the control actually relies on the formation of disordered AlSiN between the crystalline AlN nucleation layer and the crystalline silicon substrate.

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Section: Resultsmentioning

confidence: 99%

Origin(s) of Anomalous Substrate Conduction in MOVPE-Grown GaN HEMTs on Highly Resistive Silicon

Ghosh

Hinz

Fairclough

et al. 2021

ACS Appl. Electron. Mater.

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“…The layers exhibit edge-and screw-type threading dislocations (TDs) with densities ranging from well below 10 5 cm −2 to approximately 5 × 10 9 cm −2 . The TD density depends on the substrate, strain management during epitaxial growth, buffer thickness, and certain procedures to reduce the TD density, for example, optimization of the nucleation process on the substrate, epitaxial lateral overgrowth, or hightemperature annealing [1][2][3][4][5][6]. TDs are known to act as nonradiative recombination centers [7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Spatial correlation of defect-selective etching and dark luminescence spots in Al _x Ga_1−xN

Netzel,

Hagedorn,

Schön

et al. 2024

Semicond. Sci. Technol.

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Defect-selective etching with molten Ba(OH)2/MgO etch drops was performed on c-plane AlGaN layers covering the entire composition range between GaN and AlN. Regardless of the aluminum content, the etchant produced shallow, hexagonal etch pits with depth-to-diameter ratios of 1/10 – 1/100. Two predominant types of etch pits were observed, which differed in size. In addition, the etch rate decreased from the center to the edge of the area exposed to the etch drops, providing a radially symmetric variation in etch pit size. For all AlGaN compositions, the positions of the etch pits correlate perfectly with the positions of the dark luminescence spots in cathodoluminescence measurements. Areas on the AlGaN samples that were not exposed to the etching procedure showed identical dark spots with the same size and density as those in the etched regions. Additionally, the density of etch pits and dark spots corresponded to the density of threading dislocations in the AlGaN layers. These observations demonstrate that the density of threading dislocations in c-plane AlGaN layers can be determined by destructive defect-selective etching with Ba(OH)2/MgO and etch pit counting, as well as by nondestructive counting of the dark spots in cathodoluminescence images. 

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Demonstration of lateral epitaxial growth of AlN on Si (1 1 1) at low temperatures by pulsed reactive sputter epitaxy

Hörich

Borgmann

Bläsing

et al. 2021

Journal of Crystal Growth

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Nitride Semiconductors

Cited by 3 publications

References 203 publications

Origin(s) of Anomalous Substrate Conduction in MOVPE-Grown GaN HEMTs on Highly Resistive Silicon

Origin(s) of Anomalous Substrate Conduction in MOVPE-Grown GaN HEMTs on Highly Resistive Silicon

Spatial correlation of defect-selective etching and dark luminescence spots in Al _x Ga_1−xN

Demonstration of lateral epitaxial growth of AlN on Si (1 1 1) at low temperatures by pulsed reactive sputter epitaxy

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Nitride Semiconductors

Cited by 3 publications

References 203 publications

Origin(s) of Anomalous Substrate Conduction in MOVPE-Grown GaN HEMTs on Highly Resistive Silicon

Origin(s) of Anomalous Substrate Conduction in MOVPE-Grown GaN HEMTs on Highly Resistive Silicon

Spatial correlation of defect-selective etching and dark luminescence spots in Al x Ga1−x N

Demonstration of lateral epitaxial growth of AlN on Si (1 1 1) at low temperatures by pulsed reactive sputter epitaxy

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Spatial correlation of defect-selective etching and dark luminescence spots in Al _x Ga_1−xN