ICTS measurements for p-GaN Schottky contacts

Shiojima, Kenji; Sugitani, Suehiro; Sakai, Shiro

doi:10.1016/s0169-4332(01)00900-x

Cited by 10 publications

(14 citation statements)

References 10 publications

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“…We call this reversible transition a memory effect. The memory effect is often observed for the c ‐plane low‐Mg‐doped p‐GaN Schottky contacts and attributed to a large concentration of defects that were tentatively identified as Ga vacancies (V Ga ) by high‐temperature isothermal capacitance transient spectroscopy (ICTS) measurements .…”

Section: Resultsmentioning

confidence: 99%

Electrical characteristics of a‐plane low‐Mg‐doped p‐GaN Schottky contacts

Naganawa

Aoki

Son

et al. 2015

Physica Status Solidi (b)

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Electrical characteristics of a variety of Schottky contacts formed with ten metal species on the a-plane of p-type lowMg-doped GaN grown on r-plane sapphire substrates were studied. We found that while current-voltage characteristics obtained under voltage scanning show no memory effect in samples formed on a-plane samples on c-plane showed a substantial memory effects. We consider that the absence of memory effect in the a-plane p-GaN samples is originating from a smaller density of interfacial defect than that in the cplane p-GaN samples. In internal photoemission spectra, we observed two linearly increasing portions suggesting two different Schottky barriers with different heights coexisting in a contact. A potential barrier corresponding to a linear increase locating at lower photon energy typically ranged between 1.6 and 2.5 eV; and that corresponding to another linear increase locating at higher energy ranged between 0.7 and 1.7. The barrier heights showed no relevance to metal work function. The a-plane GaN surface was found to reveal a lamellar structure with stripes along [0001] direction with a randomly oriented roughness. We thus speculate that contact barrier spatially varies according to the different crystal plane.

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Section: Resultsmentioning

confidence: 99%

Electrical characteristics of a‐plane low‐Mg‐doped p‐GaN Schottky contacts

Naganawa

Aoki

Son

et al. 2015

Physica Status Solidi (b)

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“…The discrepancy between XPS and I-V measurements is more likely related to the presence of an interfacial layer, which may take the form of a native oxide or defect-containing layer. Indeed, it was shown by Shiojima et al 37 using high-temperature isothermal capacitance transient spectroscopy that the defects induced by the high Mg doping in p-GaN are essentially located at the surface vicinity and that this region acts as a series capacitance. 37,38 Therefore, when such an interfacial layer is present, the carriers have to tunnel through an additional barrier, thus resulting in an apparent SBH given by…”

Section: Resultsmentioning

confidence: 99%

Annealing and Measurement Temperature Dependence of W2B- and W2B5-Based Rectifying Contacts to p-GaN

Voss

Stafford

Thaler

et al. 2007

Journal of Elec Materi

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metallization schemes was investigated using x-ray photoelectron spectroscopy (XPS), current-voltage (I-V), and Auger electron spectroscopy measurements. The Schottky barrier height (SBH) determined from XPS is 2.71 eV and 2.87 eV for as-deposited W 2 B-and W 2 B 5 -based contacts, respectively. By comparison, fitting of the I-V curves using the thermionic field emission model gives unphysical SBHs > 4 eV due to the presence of an interfacial layer acting as an additional barrier to carrier transport. Upon annealing to~600-700°C, the diodes show slight deterioration in rectifying behavior due to the onset of metallurgical reactions with the GaN. The experimental dependence of the reverse leakage current on bias and measurement temperature is inconsistent with both thermionic emission and thermionic field emission models, suggesting that leakage must originate from other mechanisms such as surface leakage or generation in the depletion layer through deep-level defects.

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“…We have observed the memory effect in the Al 0.02 Ga 0.98 N and In 0.02 Ga 0.98 N samples and a large single H-ICTS peak. We have reported in our previous papers [15,16] that the origin of this peak in the p-GaN samples is the gallium vacancy (V Ga ) near to the interface. On the other hand, it has been reported that the Al vacancy (V Al ) and/or the In vacancy (V In ) also exist in AlGaN and/or InGaN with high Al and/or In contents [17,18].…”

Section: Discussionmentioning

confidence: 99%

“…In the series of samples prepared, the ICTS signal was not detected when the filling and bias voltage conditions were specifically set for detecting defects near the depletion layer edge. In this study, since we focused on the defects in the vicinity of the interface we chose a forward filling pulse of 10 V for 1 min and a stationary bias of 0 V as in the previous study .…”

Section: Sample Preparation and Measurement Conditionsmentioning

confidence: 99%

Electrical characteristics of low‐Mg‐doped p‐AlGaN and p‐InGaN Schottky contacts

Aoki

Tachibana

Shiojima

2015

Physica Status Solidi (b)

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Electrical characteristics of low‐Mg‐doped p‐Al0.02–0.07Ga0.98–0.93N and p‐In0.02Ga0.98N Schottky contacts were investigated. A memory effect was revealed in the current–voltage (I–V) characteristics, which is found also in p‐GaN contacts and may be due to charge and discharge of holes to acceptor‐type interfacial defects. High‐temperature isothermal transient spectroscopy revealed that the defect densities in the Al0.02Ga0.98N and In0.02Ga0.98N samples were nearly half that in the GaN samples. A large reverse current with a memory effect was observed in the In0.02Ga0.98N contacts. It was suggested that current can flow via relatively shallow acceptor‐type interfacial defects. For the AlxGa1−xN with x = 0.04 and 0.07, I–V characteristics became leaky. The Schottky barrier heights estimated from the photoresponse experiment were higher than the values estimated from the bandgap by 0.19, 0.21, 0.20, and 0.21 eV for Al0.02Ga0.98N, Al0.04Ga0.96N, Al0.07Ga0.93N, and In0.02Ga0.98N samples, respectively. A probable explanation for such discrepancies may be due to the total charge amount of the interfacial states, which varied the electric field and the barrier lowering. It was found that even though the Al or In content was only as small as 2%, the electrical characteristics of the contacts changed significantly.

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ICTS measurements for p-GaN Schottky contacts

Cited by 10 publications

References 10 publications

Electrical characteristics of a‐plane low‐Mg‐doped p‐GaN Schottky contacts

Electrical characteristics of a‐plane low‐Mg‐doped p‐GaN Schottky contacts

Annealing and Measurement Temperature Dependence of W2B- and W2B5-Based Rectifying Contacts to p-GaN

Electrical characteristics of low‐Mg‐doped p‐AlGaN and p‐InGaN Schottky contacts

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