Multicycle rapid thermal annealing technique and its application for the electrical activation of Mg implanted in GaN

Feigelson, Boris N.; Anderson, Travis J.; Abraham, M. M.; Freitas, J. A.; Hite, Jennifer K.; Eddy, Charles R.; Kub, Francis J.

doi:10.1016/j.jcrysgro.2011.12.016

Cited by 122 publications

(108 citation statements)

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“…One recent study reported the formation of a p-type conductive layer by Mg ion implantation. Also, there are some reports of forming the p-type layer evaluated by Hall measurements [5] [6]. However, Mg ion implantation hasn't been applied to GaN device fabrication in the past.…”

Section: Introductionmentioning

confidence: 99%

Mg Tilted-Angle Ion Implantation for Threshold Voltage Control and Suppression of the Short Channel Effect in GaN MISFETs

Kasai¹,

Oikawa²,

Mishima³

et al. 2017

MSCE

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This paper demonstrates that threshold voltages of GaN MISFET are controllable by varying the Mg ion doses for Mg ion implantation. Furthermore, it demonstrates for the first time that the short channel effect can be suppressed using a halo structure that has a p-layer in channel regions adjacent to source/ drain regions using tilt ion implantation. A device with a Mg dose of 8 × 10 13 /cm 2 achieved maximum drain current of 240 mA/mm and a transconductance of 40 mS/mm. These results indicate a definite potential for the use of our new process in GaN MISFETs for applications in power switching devices.

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Section: Introductionmentioning

confidence: 99%

Mg Tilted-Angle Ion Implantation for Threshold Voltage Control and Suppression of the Short Channel Effect in GaN MISFETs

Kasai¹,

Oikawa²,

Mishima³

et al. 2017

MSCE

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“…• C) for the activation anneal, 6 which are significantly higher than the decomposition temperature of GaN at atmospheric pressures (845…”

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confidence: 98%

“…z E-mail: jordan.greenlee@gmail.com with activation efficiencies of over 8%. 6,16 MRTA utilizes the repetition of heating pulses to anneal GaN at temperatures above 1300…”

mentioning

confidence: 99%

“…15 More recently, the development of a multicycle rapid thermal annealing (MRTA) technique has enabled Mg activation after implantation with activation efficiencies of over 8%. 6,16 MRTA utilizes the repetition of heating pulses to anneal GaN at temperatures above 1300…”

mentioning

confidence: 99%

“…Additionally, an AlN cap is used in the MRTA process to prevent nitrogen loss at the GaN surface. 6 The MRTA process consists of two separate, consequent steps (Fig. 1a).…”

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confidence: 99%

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Symmetric Multicycle Rapid Thermal Annealing: Enhanced Activation of Implanted Dopants in GaN

Greenlee

Feigelson

Anderson

et al. 2015

ECS J. Solid State Sci. Technol.

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Selectively activated p-type regions are necessary for many electronic devices that require planar processing. The standard process of implanting p-type dopants, such as Mg, in GaN is notoriously more difficult than in other material systems, as the extremely high temperatures required to activate the implanted Mg also damage the GaN surface. In this research, a novel annealing technique is introduced for this purpose -symmetric multicycle rapid thermal annealing (SMRTA). It is shown that SMRTA is superior to the earlier developed multicycle rapid thermal annealing (MRTA) in terms of improvement of the crystalline quality of implanted GaN. The SMRTA technique was applied to Mg-implanted GaN to realize a rectifying junction. The annealing process detailed in this research will be a key enabling step for future GaN-based GaN and other III-nitride based semiconductors have received a great deal of attention from the research community due to favorable material properties which include a tunable direct bandgap, radiation hardness, and a favorable Baliga figure of merit compared to Si and SiC.1,2 The doping of p-type GaN during growth is challenging and has been the focus of numerous studies because it has many potential transformative applications in power electronics and optoelectronics.3 P-type dopant implantation and activation adds additional complexity to the synthesis of p-type GaN. The ability to implant and activate p-type species in GaN is a key enabling process for devices that require selective area doping. Device structures that benefit from the ability to selectively implant and activate p-type dopants in GaN include implanted guard rings for electric field spreading, implanted current blocking layers for current aperture vertical electron transistors, and implanted regions below contacts to lower contact resistance. 4,5 Unfortunately, the implantation and activation of Mg in GaN is difficult because of the high temperatures required (over 1300• C) for the activation anneal, 6 which are significantly higher than the decomposition temperature of GaN at atmospheric pressures (845 • C). 7 The decomposition of GaN occurs due to a loss of nitrogen and results in surface damage and the formation of N vacancies, which are compensating donors. 8To avoid GaN decomposition at the elevated annealing temperatures required for Mg activation, high pressure environments and non-equilibrium annealing conditions combined with capping layers have been investigated. 9,10 GaN can be successfully annealed at about 1500• C, but a 1.5 GPa overpressure of N 2 is necessary to avoid surface degradation.11 Such high gas pressures also require a complicated experimental setup and are not easily industrial scalable. 12A second, more scalable, alternative to the high pressure annealing of GaN relies on using non-equilibrium annealing conditions. For this type of annealing, a capping layer is used to prevent nitrogen loss from the GaN surface. Depending on the material, structure, and thickness of the capping layer, higher annealin...

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Lattice Location Studies of the Amphoteric Nature of Implanted Mg in GaN

Wahl

Correia

Costa

et al. 2021

Adv Elect Materials

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Despite the renewed interest in ion implantation doping of GaN, efficient electrical activation remains a challenge. The lattice location of 27Mg is investigated in GaN of different doping types as a function of implantation temperature and fluence at CERN's ISOLDE facility. The amphoteric nature of Mg is elucidated, i.e., the concurrent occupation of substitutional Ga and interstitial sites: following room temperature ultra‐low fluence (≈2 × 1010 cm−2) implantation, the interstitial fraction of Mg is highest (20–24%) in GaN pre‐doped with stable Mg during growth, and lowest (2–6%) in n‐GaN:Si, while undoped GaN shows an intermediate interstitial fraction of 10–12%. Both for p‐ and n‐GaN prolonged implantations cause interstitial 27Mg to approach the levels found for undoped GaN. Implanting above 400 °C progressively converts interstitial Mg to substitutional Ga sites due to the onset of Mg interstitial migration (estimated activation energy 1.5–2.3 eV) and combination with Ga vacancies. In all sample types, implantations above a fluence of 1014 cm−2 result in >95% substitutional Mg. Ion implantation is hence a very efficient method to introduce Mg into substitutional Ga sites, i.e., challenges toward high electrical activation of implanted Mg are not related to lack of substitutional incorporation.

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Multicycle rapid thermal annealing technique and its application for the electrical activation of Mg implanted in GaN

Cited by 122 publications

References 20 publications

Mg Tilted-Angle Ion Implantation for Threshold Voltage Control and Suppression of the Short Channel Effect in GaN MISFETs

Mg Tilted-Angle Ion Implantation for Threshold Voltage Control and Suppression of the Short Channel Effect in GaN MISFETs

Symmetric Multicycle Rapid Thermal Annealing: Enhanced Activation of Implanted Dopants in GaN

Lattice Location Studies of the Amphoteric Nature of Implanted Mg in GaN

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