Photoelectrochemical liftoff of LEDs grown on freestanding c-plane GaN substrates

Hwang, David J.; Yonkee, Benjamin P.; Addin, Burhan Saif; Farrell, Robert M.; Nakamura, Shuji; Speck, James S.; DenBaars, Steven P.

doi:10.1364/oe.24.022875

Cited by 37 publications

(20 citation statements)

References 25 publications

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“…Bulk GaN substrates are becoming available commercially, but their high cost and limited availability pose challenges for widespread adoption. The use of epitaxial lift-off (ELO) offers an approach to address these issues [10]- [13]. Removing the substrate and bonding the lifted-off device film to a high-thermal-conductivity substrate eliminates the thermal resistance associated with conventional substrates through direct thermal and electrical bonding to the heat sink.…”

Section: High-voltage Vertical Gan P-n Diodes By Epitaxial Liftoff Frmentioning

confidence: 99%

High-Voltage Vertical GaN p-n Diodes by Epitaxial Liftoff From Bulk GaN Substrates

Wang

McCarthy

Youtsey

et al. 2018

IEEE Electron Device Lett.

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High-performance vertical GaN-based p-n junction diodes fabricated using bandgap selective photoelectrochemical etching-based epitaxial liftoff (ELO) from bulk GaN substrates are demonstrated. The epitaxial GaN layers and pseudomorphic InGaN release layer were grown by MOCVD on bulk GaN substrates. A comparison study was performed between devices after liftoff processing (after transfer to a Cu substrate) and nominally identical control devices on GaN substrates without the buried release layer or ELO-related processing. ELO and bonded devices exhibit nearly identical electrical performance and improved thermal performance, compared with the control devices on full-thickness GaN substrates. The breakdown voltage, ideality factor, and forward turn-ON performance were found to be nearly identical, indicating that the transfer process does not degrade the quality of the p-n junctions. The devices exhibit turn-ON voltages of 3.1 V at a current density of 100 A/cm 2 , with a specific ON-resistance (R ON) of 0.2-0.5 m • cm 2 at 5 V and a breakdown voltage (V br) of 1.3 kV. Both optical and electrical characterization techniques show that the thermal resistance of ELO devices bonded to a Cu carrier is approximately 30% lower than that for control devices on GaN substrates. Index Terms-GaN p-n junctions, epitaxial lift-off, thermal resistance. I. INTRODUCTION V ERTICAL GaN (and related III-N materials)-based devices are promising for power electronics due to both the exceptional properties of the III-N material system and the advantages of vertical device architectures [1]-[7]. However, vertical GaN-based device performance is often limited due to the use of lattice-mismatched foreign substrates, resulting in high dislocation densities as well as limited thermal conductivity for heat removal [8], [9].

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Section: High-voltage Vertical Gan P-n Diodes By Epitaxial Liftoff Frmentioning

confidence: 99%

High-Voltage Vertical GaN p-n Diodes by Epitaxial Liftoff From Bulk GaN Substrates

Wang

McCarthy

Youtsey

et al. 2018

IEEE Electron Device Lett.

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“…Moreover, these photonic devices are mostly built on sapphire, bulk GaN, and SiC substrates, which are rigid, and cannot meet the growing demand for new functionalities, for example, wearable devices, which require flexible electronic and photonic device components. Although using mechanical polishing, mechanical peeling off, dry techniques such as laser lift‐off, and epitaxial lift‐off such as selective wet etching of sacrificial layer or entire substrate, these rigid substrates can be removed and III‐nitride epilayers can be transferred to flexible substrates. These substrate removing processes, together with the subsequent processing steps to fabricate and assemble the micro‐ and nano‐scale devices for flexible photonics, are highly complicated; and how to maintain the quality of the epilayers at a large scale has remained challenging …”

Section: Introductionmentioning

confidence: 99%

Recent Advances on III‐Nitride Nanowire Light Emitters on Foreign Substrates – Toward Flexible Photonics

Sun

2018

Physica Status Solidi (a)

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Flexible electronic and photonic devices have received broad interest in the past, due to their compact size, new functionalities, and other merits which devices on rigid substrates do not possess. In this context, the author review recent progresses on flexible III-nitride nanowire photonic devices, focusing on LEDs and lasers. The formation of III-nitride nanowire LEDs and lasers directly on various foreign substrates is firstly described, paving the way to flexible IIInitride nanowire photonic devices through either direct growth on or transfer to flexible substrates. The realization of flexible III-nitride nanowire LEDs through various transfer processes is further detailed. In the end, the challenges of IIInitride nanowire technology for flexible integrated photonics are discussed.

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“…However, ELO of III‐nitrides is more challenging because of the lack of lattice‐matched release layers and wet etches that have high selectivity and fast etching rates. ELO processing of GaN films has been demonstrated by several techniques, including laser lift‐off, selective wet etching of release layers, grinding or etching of substrates, and band gap selective photoelectrochemical (PEC) etching techniques . In addition, several techniques have been reported to separate GaN devices from foreign substrates, but these processes are not currently compatible with native GaN substrates.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, a band gap selective PEC technique is used for the ELO processing. PEC etching utilizes illumination above the semiconductor band gap to photogenerate holes for facilitating the oxidation and subsequent dissolution of the semiconductor release layer.…”

Section: Introductionmentioning

confidence: 99%

Ion‐Implant Isolated Vertical GaN p‐n Diodes Fabricated with Epitaxial Lift‐Off From GaN Substrates

Wang

McCarthy

Youtsey

et al. 2018

Physica Status Solidi (a)

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Ion-implant isolated vertical GaN p-n junction diodes fabricated with epitaxial lift-off (ELO) from GaN substrates are demonstrated. For the ELO process, a band-gap selective photoelectrochemical (PEC) wet etch with a pseudomorphic InGaN release layer is utilized. Compared with devices isolated using mesa etching, the ion-implant isolated devices exhibit more ideal forward current-voltage characteristics and lower leakage currents. Devices are also compared with and without ELO processing. Devices measured after ELO processing and mounting to metallized carrier substrates show similar electrical performance to GaN-on-GaN control samples without ELO processing. No indication of material quality degradation is found on the ELO devices. The ELO devices exhibit turn-on voltages of 3.15 V (at a current density of 100 A cm À2 ), with specific on resistance (R on ) of 0.52 mΩ cm 2 at 4.8 V and breakdown voltage (V br ) approximately of 750 V.

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Photoelectrochemical liftoff of LEDs grown on freestanding c-plane GaN substrates

Cited by 37 publications

References 25 publications

High-Voltage Vertical GaN p-n Diodes by Epitaxial Liftoff From Bulk GaN Substrates

High-Voltage Vertical GaN p-n Diodes by Epitaxial Liftoff From Bulk GaN Substrates

Recent Advances on III‐Nitride Nanowire Light Emitters on Foreign Substrates – Toward Flexible Photonics

Ion‐Implant Isolated Vertical GaN p‐n Diodes Fabricated with Epitaxial Lift‐Off From GaN Substrates

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