Low-voltage GaN tunnel junctions enabled by a thermally reconstructed InGaN sacrificial interlayer

Le résumé fourni par la source

Low-voltage tunnel junctions (TJs) are essential for vertically integrated III-nitride emitters, yet their voltage penalty limits monolithic multicolor integration. We report a GaN-based TJ in which a 5 nm InGaN sacrificial interlayer is thermally reconstructed during a subsequent in-reactor step, producing a laterally redistributed In-rich tunneling interface. Four metalorganic chemical vapor deposition (MOCVD)-grown blue LED samples are compared: a p+-GaN/n+-GaN homojunction (LED A), the same homojunction after a 1000 °C, 3 min treatment (LED A-HT), a TJ with an intact 5 nm n-In0.3Ga0.7N interlayer (LED B), and its reconstructed counterpart (LED C). Cross-sectional TEM and In elemental mapping show a continuous interlayer in TJ B, whereas TJ C contains laterally redistributed In-rich regions and nanoscale void-like structural features; the blue InGaN/GaN quantum wells remain clearly resolved after the thermal process. LED C exhibits a device turn-on voltage of 3.4 V, compared with 4.1 V for LED B and 4.6 V for LED A; LED A-HT shows no comparable reduction. Similar peak wavelengths and linewidths among the four LEDs show that the blue test active region retains its peak position and spectral width after the different TJ treatments. Incorporation of the reconstructed TJ into a monolithic InGaN blue/green/red stack yields selectively driven three-color electroluminescence, wafer-scale PL peak-wavelength standard deviations below 3 nm, and an experimental CIE 1931 triangle area equal to 72.9% of the BT.2020 triangle area at the stated operating points. These results provide an MOCVD-compatible approach to reducing the voltage penalty of buried nitride TJs in vertically integrated emitters.

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