Electron-irradiation-induced deep level in n-type GaN

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Kim

et al. 1998

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144

Deep centers in Si-doped n-GaN layers grown by reactive molecular beam epitaxy have been studied by deep-level transient spectroscopy as a function of growth conditions. Si-doped GaN samples grown on a Si-doped n+-GaN contact layer at 800 °C show a dominant trap C1 with activation energy ET=0.44 eV and capture cross-section σT=1.3×10−15 cm−2, while samples grown at 750 °C on an undoped semi-insulating GaN buffer show prominent traps D1 and E1, with ET=0.20 eV and σT=8.4×10−17 cm2, and ET=0.21 eV and σT=1.6×10−14 cm2, respectively. Trap E1 is believed to be related to a N-vacancy defect, since the Arrhenius signature for E1 is very similar to the previously reported trap E, which is produced by 1-MeV electron irradiation in GaN materials grown by both metalorganic chemical-vapor deposition and hydride vapor-phase epitaxy.

mentioning

confidence: 70%

Section: T Mmentioning

confidence: 99%

Deep centers in n-GaN grown by reactive molecular beam epitaxy

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Kim

et al. 1998

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144

“…5 Recently, a strong effort by several groups has been devoted to the study of irradiation-induced defects in GaN and related compounds. [6][7][8][9][10] Most of the results are still not fully understood, but some useful conclusions have already emerged. As an example, for 30 years the N vacancy V N has been considered to be the dominant donor in GaN, 11 but it has just recently been shown that this assumption is not true, 7 at least for the best, present-day material.…”

Section: On the Main Irradiation-induced Defect In Ganmentioning

confidence: 99%

On the main irradiation-induced defect in GaN

Polenta

Look

2000

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We show that the usual Arrhenius analysis of the main electron-irradiation-induced defect trap in n-type GaN, observed by deep-level transient spectroscopy (DLTS), is not sufficiently accurate. Instead, an exact fitting of the DLTS spectrum for this trap reveals two components, each of which has a thermal energy near 60 meV, not the apparent 140–200 meV, as given in other DLTS studies. This result resolves the discrepancy between Hall-effect and DLTS determinations of the thermal energy of this defect center.

“…According to a detailed study by Wosinski 7 of a dislocation-related electron trap ͑a line-defect͒ in plastically deformed n-type GaAs crystals, an increase in the slope of the n T versus ln(W f ) lines means an increase in the density of strain-related dislocations. Therefore, in our case, we believe that the plasma treatments do not cause any meaningful increase in dislocation density, even under an etching biasvoltage of Ϫ150 V. Trap D, with E T ϭ0.23-0.27 eV and n ϭ(1 -2)ϫ10 Ϫ15 cm 2 , has been observed in thin GaN layers by many groups, using various techniques, including hydride vapor phase epitaxy ͑HPVE͒, [8][9][10] MOCVD, [11][12][13] and MBE. 14,15 Three of these studies are consistent with the proposition that trap D is at least sometimes related to threading dislocations.…”

mentioning

confidence: 99%

Plasma-etching-enhanced deep centers in n-GaN grown by metalorganic chemical-vapor deposition

Wang

Han

et al. 2003

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By using deep-level transient spectroscopy (DLTS), deep centers have been characterized in unintentionally doped n-GaN samples grown by metalorganic chemical-vapor deposition and subjected to inductively coupled plasma reactive ion etching. At least six DLTS traps exist in the control sample: A1 (∼0.90 eV), Ax (∼0.72 eV), B (0.61 eV), C1 (0.44 eV), D (0.25 eV), and E1 (0.17 eV), with B dominant. Then, as the etching bias-voltage increases from −50 to −150 V, trap D increases strongly and becomes dominant, while traps A1, C (0.34 eV), and E1 increase at a slower rate. Trap B, on the other hand, is nearly unchanged. Previous electron-irradiation studies are consistent with the E1 traps being N-vacancy related. It is likely that the D traps are also, except that they are in the regions of dislocations.