Thermal ionization energy of Si and Mg in AlGaN

Katsuragawa, Maki; Sota, Shigetoshi; Komori, Miho; Anbe, Chitoshi; Takeuchi, Tetsuya; Sakai, Hiromitsu; Amano, Hiroshi; Akasaki, Isamu

doi:10.1016/s0022-0248(98)00345-5

Cited by 138 publications

(91 citation statements)

References 9 publications

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“…Bremser et al [31,32] reported a failure to achieve p-type conductivity with Mg doping for x > 0.13. Other studies have also found a decrease in achievable hole concentration when the Al content of the AlGaN alloy is increased [40][41][42].…”

Section: Magnesium In Gan and Alnmentioning

confidence: 84%

Defects and Defect Reactions in Semiconductor Nitrides

et al. 1999

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We report a comprehensive investigation of native point defects and impurities in GaN, MN, and AlGaN alloys, with the goal of understanding doping limitations in nitride semiconductors. Unintentional incorporation of impurities (mainly oxygen) explains the tendency of nitride semiconductors to exhibit n-type conductivity. Silicon is the n-type dopant of choice; it remains shallow in AlGaN up to high Al content, while oxygen undergoes a DX transition. Experimental evidence for DX centers will be discussed. In p-type material, Mg doping is hindered by an increase in ionization energy with increasing Al content in AlGaN, and by nitrogen vacancies acting as compensating centers. Complex formation between magnesium and oxygen and between magnesium and nitrogen vacancies will be discussed.

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Section: Magnesium In Gan and Alnmentioning

confidence: 84%

Defects and Defect Reactions in Semiconductor Nitrides

et al. 1999

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“…Still, the hole concentration that can be achieved is lower than desired, particularly for applications such as high p-type doping near metal contacts for improved Ohmic contact behavior. In addition, the hole concentration that can be achieved with Mg doping has been observed to decrease rapidly with increasing Al content x in Al x Ga 1-x N. 5,8,9,10 Magnesium exhibits no tendency to form deep levels (so called AX levels, analogous to DX for donors), 33 thus ruling out a shallow-deep transition as the source of the drop in hole concentration. We also found, for Mg in GaN, that incorporation of Mg on interstitial sites, or on nitrogen sites, is energetically unfavorable.…”

Section: Results For P-type Dopingmentioning

confidence: 99%

“…Other studies have also found a decrease in achievable hole concentration when the Al content of the AlGaN alloy is increased. 8,9,10 Useful information about the doping characteristics of nitride semiconductors can be obtained by performing first-principles calculations. We previously performed comprehensive studies of doping in n-type 11,12 and p-type 6,7,13 GaN.…”

Section: Introductionmentioning

confidence: 99%

Doping of AlGaN Alloys

Walle

Stampfl

Neugebauer

et al. 1999

MRS Internet j. nitride semicond. res.

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Nitride-based device structures for electronic and optoelectronic applications usually incorporate layers of Al x Ga 1-x N, and n-and p-type doping of these alloys is typically required. Experimental results indicate that doping efficiencies in Al x Ga 1-x N are lower than in GaN. We address the cause of these doping difficulties, based on results from first-principles densityfunctional-pseudopotential calculations. For n-type doping we will discuss doping with oxygen, the most common unintentional donor, and with silicon. For oxygen, a DX transition occurs which converts the shallow donor into a negatively charged deep level. We present experimental evidence that oxygen is a DX center in Al x Ga 1-x N for x>~0.3. For p-type doping, we find that compensation by nitrogen vacancies becomes increasingly important as the Al content is increased. We also find that the ionization energy of the Mg acceptor increases with alloy composition x. To address the limitations on p-type doping we have performed a comprehensive investigation of alternative acceptor impurities; none of the candidates exhibits characteristics that surpass those of Mg in all respects.

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“…Due to high polarization fields and large defect density, the illumination power and internal efficiency of nitride based devices is low [2,3,4,5,6,7]. Due to low doping efficiencies, in such UV LEDs, enhancing carrier injection in the active region remains a great challenge [8,9]. To improve internal quantum efficiency, grading has been used in InGaN/AlInGaN quantum wells (QW) based LEDs [10,11,12] with reported 5-6 times enhancement in radiative recombination.…”

Section: Introductionmentioning

confidence: 99%