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Near-surface processing on AlGaN/GaN heterostructures: a nanoscale electrical and structural characterization.

Greco G, Giannazzo F, Frazzetto A, Raineri V, Roccaforte F - Nanoscale Res Lett (2011)

Bottom Line: In particular, a CHF3-based plasma process in the gate region resulted in a shift of the threshold voltage in HEMT devices towards less negative values.Two-dimensional current maps acquired by C-AFM on the sample surface allowed us to monitor the local electrical modifications induced by the plasma fluorine incorporated in the material.The results are compared with a recently introduced gate control processing: the local rapid thermal oxidation process of the AlGaN layer.By this process, a controlled thin oxide layer on surface of AlGaN can be reliably introduced while the resistance of the layer below increase locally.

View Article: PubMed Central - HTML - PubMed

Affiliation: Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII n, 5, Zona Industriale, 95121 Catania, Italy. fabrizio.roccaforte@imm.cnr.it.

ABSTRACT
The effects of near-surface processing on the properties of AlGaN/GaN heterostructures were studied, combining conventional electrical characterization on high-electron mobility transistors (HEMTs), with advanced characterization techniques with nanometer scale resolution, i.e., transmission electron microscopy, atomic force microscopy (AFM) and conductive atomic force microscopy (C-AFM). In particular, a CHF3-based plasma process in the gate region resulted in a shift of the threshold voltage in HEMT devices towards less negative values. Two-dimensional current maps acquired by C-AFM on the sample surface allowed us to monitor the local electrical modifications induced by the plasma fluorine incorporated in the material.The results are compared with a recently introduced gate control processing: the local rapid thermal oxidation process of the AlGaN layer. By this process, a controlled thin oxide layer on surface of AlGaN can be reliably introduced while the resistance of the layer below increase locally.

No MeSH data available.


Related in: MedlinePlus

TEM analysis of the heterojunction AlGaN/GaN after CHF3 plasma process. A defect-rich region near the surface is visible.
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Figure 3: TEM analysis of the heterojunction AlGaN/GaN after CHF3 plasma process. A defect-rich region near the surface is visible.

Mentions: Figure 3 shows cross-section TEM micrographs of our AlGaN/GaN heterostructure taken in the proximity of the gate of the HEMT device subjected to the plasma process. The dark contrast in the AlGaN region underneath the Pt gate contact can be associated to a considerable amount of crystalline imperfections (defects). This defect-rich interface region could be highly resistive and could affect the leakage current behaviour. Indeed also Chu et al. [10] suggested that the fluorine plasma can react with GaN (or AlGaN) to form non volatile F-containing compounds, leading to the creation of an insulating surface that blocks the leakage current.


Near-surface processing on AlGaN/GaN heterostructures: a nanoscale electrical and structural characterization.

Greco G, Giannazzo F, Frazzetto A, Raineri V, Roccaforte F - Nanoscale Res Lett (2011)

TEM analysis of the heterojunction AlGaN/GaN after CHF3 plasma process. A defect-rich region near the surface is visible.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211179&req=5

Figure 3: TEM analysis of the heterojunction AlGaN/GaN after CHF3 plasma process. A defect-rich region near the surface is visible.
Mentions: Figure 3 shows cross-section TEM micrographs of our AlGaN/GaN heterostructure taken in the proximity of the gate of the HEMT device subjected to the plasma process. The dark contrast in the AlGaN region underneath the Pt gate contact can be associated to a considerable amount of crystalline imperfections (defects). This defect-rich interface region could be highly resistive and could affect the leakage current behaviour. Indeed also Chu et al. [10] suggested that the fluorine plasma can react with GaN (or AlGaN) to form non volatile F-containing compounds, leading to the creation of an insulating surface that blocks the leakage current.

Bottom Line: In particular, a CHF3-based plasma process in the gate region resulted in a shift of the threshold voltage in HEMT devices towards less negative values.Two-dimensional current maps acquired by C-AFM on the sample surface allowed us to monitor the local electrical modifications induced by the plasma fluorine incorporated in the material.The results are compared with a recently introduced gate control processing: the local rapid thermal oxidation process of the AlGaN layer.By this process, a controlled thin oxide layer on surface of AlGaN can be reliably introduced while the resistance of the layer below increase locally.

View Article: PubMed Central - HTML - PubMed

Affiliation: Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII n, 5, Zona Industriale, 95121 Catania, Italy. fabrizio.roccaforte@imm.cnr.it.

ABSTRACT
The effects of near-surface processing on the properties of AlGaN/GaN heterostructures were studied, combining conventional electrical characterization on high-electron mobility transistors (HEMTs), with advanced characterization techniques with nanometer scale resolution, i.e., transmission electron microscopy, atomic force microscopy (AFM) and conductive atomic force microscopy (C-AFM). In particular, a CHF3-based plasma process in the gate region resulted in a shift of the threshold voltage in HEMT devices towards less negative values. Two-dimensional current maps acquired by C-AFM on the sample surface allowed us to monitor the local electrical modifications induced by the plasma fluorine incorporated in the material.The results are compared with a recently introduced gate control processing: the local rapid thermal oxidation process of the AlGaN layer. By this process, a controlled thin oxide layer on surface of AlGaN can be reliably introduced while the resistance of the layer below increase locally.

No MeSH data available.


Related in: MedlinePlus