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1.
M. Kocan G.A. Umana-Membreno J.S. Chung F. Recht L. McCarthy S. Keller U.K. Mishra G. Parish B.D. Nener 《Journal of Electronic Materials》2007,36(9):1156-1159
This paper reports results of a study of non-alloyed ohmic contacts on Si-implanted AlGaN/GaN heterostructures, obtained from
current–voltage characteristics of transfer-length method (TLM) test structures. It is shown that the measured contact resistance
from the Ti/Au/Ni metal contacts, deposited on Si-implanted regions, to the two-dimensional electron gas channel at the AlGaN/GaN
heterointerface of the non-implanted region, is formed by three different components: (i) contact resistance between the metal␣and
the semiconductor (0.60 ± 0.16 Ω mm), (ii) resistance of the implanted region (0.62 ± 0.03 Ω mm) and (iii) an additional resistance
(0.72 ± 0.24 Ω mm) giving a total value of 1.9 ± 0.3 Ω mm. The specific ohmic contact resistance was determined to be (2.4 ± 0.5) × 10−5 Ω cm2. 相似文献
2.
Temperature-Dependent Characterization of AlGaN/GaN HEMTs: Thermal and Source/Drain Resistances 总被引:1,自引:0,他引:1
Menozzi R. Umana-Membreno G.A. Nener B.D. Parish G. Sozzi G. Faraone L. Mishra U.K. 《Device and Materials Reliability, IEEE Transactions on》2008,8(2):255-264
This paper shows the application of simple dc techniques to the temperature-dependent characterization of AlGaN/ GaN HEMTs in terms of the following: 1) thermal resistance and 2) ohmic series resistance (at low drain bias). Despite their simplicity, these measurement techniques are shown to give valuable information about the device behavior over a wide range of ambient/channel temperatures. The experimental results are validated by comparison with independent measurements and numerical simulations. 相似文献
3.
M. Kocan G.A. Umana-Membreno M.R. Kilburn I.R. Fletcher F. Recht L. McCarthy U.K. Mishra B.D. Nener G. Parish 《Journal of Electronic Materials》2008,37(5):554-557
This paper reports results of scanning ion probe studies of silicon implantation profiles in source and drain regions of AlGaN/GaN
high-electron-mobility transistor (HEMT) heterostructures. It is shown that both the undoped channel length and the transition
region between implanted and non- implanted regions become wider with increasing depth in the structure. These results may
explain the previously reported existence of resistance associated with the transition region between implanted and non-implanted
semiconductor regions in AlGaN/GaN HEMT heterostructures with non-alloyed Si-implanted source and drain ohmic contact regions. 相似文献
4.
Martin Kocan Felix Recht Gilberto A. Umana-Membreno Matt R. Kilburn Brett D. Nener Umesh K. Mishra Giacinta Parish 《Solid-state electronics》2011,56(1):56-59
We report on the effect of implantation angle on contact resistance of non-alloyed ohmic contacts to selectively implanted source/drain regions in AlGaN/GaN high electron mobility transistor (HEMT) heterostructures. Three different components of contact resistance are observed for such contacts: (i) contact resistance between the metal and the semiconductor, (ii) resistance of the implanted region and (iii) an additional resistance attributed to a transition region between implanted and non-implanted region. This third component varies strongly with implantation angle. The variation with implantation angle shows that the ratio of lateral implantation damage to penetration depth is critical for implantation of AlGaN/GaN HEMT source/drain contact regions. Our results also show that increasing the implantation angle in combination with reducing the implantation width can reduce contact resistance. 相似文献
5.
Tamara B. Fehlberg Chad S. Gallinat Gilberto A. Umana-Membreno Gregor Koblmüller Brett D. Nener James S. Speck Giacinta Parish 《Journal of Electronic Materials》2008,37(5):593-596
A quantitative mobility spectrum analysis (QMSA) of multiple magnetic field data has been used to determine the transport
properties of bulk and surface electron species in InN films, grown by plasma-assisted molecular beam epitaxy (PAMBE) with
varying substrate temperatures and In/N flux ratios. While all films have similar bulk electron densities, ∼4 × 1017 cm−3, the highest mobility was obtained in the highest growth temperature film (3100 cm2/V s at 150 K), while In-rich growth also gave good mobility values even at a much lower growth temperature. The surface sheet
electron concentration increased with surface roughness, which increased with N-flux during growth. 相似文献
6.
J. Antoszewski G.A. Umana-Membreno L. Faraone 《Journal of Electronic Materials》2012,41(10):2816-2823
In this paper the recently developed high-resolution mobility spectrum analysis is demonstrated. In a number of simulations the high resolution of the algorithm is demonstrated in the high and low mobility ranges. The effect of random noise, maximum magnetic field limit, and the number of magnetic field points used in the experiment is also demonstrated. Also discussed are requirements critical for obtaining high-quality experimental data. The application of this new algorithm to complex semiconductor structures to study lateral and vertical transport is also demonstrated, resulting in insight into previously unavailable details. 相似文献
7.
/sup 60/Co gamma irradiation effects on n-GaN Schottky diodes 总被引:1,自引:0,他引:1
Umana-Membreno G.A. Dell J.M. Parish G. Nener B.D. Faraone L. Mishra U.K. 《Electron Devices, IEEE Transactions on》2003,50(12):2326-2334
The effect of /spl gamma/-ray exposure on the electrical characteristics of nickel/n-GaN Schottky barrier diodes has been investigated using current-voltage (I-V), capacitance-voltage (C-V), and deep-level transient spectroscopy (DLTS) measurements. The results indicate that /spl gamma/-irradiation induces an increase in the effective Schottky barrier height extracted from C-V measurements. Increasing radiation dose was found to degrade the reverse leakage current, whereas its effect on the forward I-V characteristics was negligible. Low temperature (/spl les/50) post-irradiation annealing after a cumulative irradiation dose of 21 Mrad(Si) was found to restore the reverse I-V characteristics to pre-irradiation levels without significantly affecting the radiation-induced changes in C-V and forward I-V characteristics. Three shallow radiation-induced defect centers with thermal activation energies of 88 104 and 144 meV were detected by DLTS with a combined production rate of 2.12 /spl times/ 10/sup -3/ cm/sup -1/. These centers are likely to be related to nitrogen-vacancies. The effect of high-energy radiation exposure on device characteristics is discussed taking into account possible contact inhomogeneities arising from dislocations and interfacial defects. The DLTS results indicate that GaN has an intrinsically low susceptibility to radiation-induced material degradation, yet the effects observed in the Schottky diode I-V and C-V characteristics indicate that the total-dose radiation hardness of GaN devices may be limited by susceptibility of the metal-GaN interface to radiation-induced damage. 相似文献
8.
G.A. Umana-Membreno T.B. FehlbergS. Kolluri D.F. BrownG. Parish B.D. NenerS. Keller U.K. MishraL. Faraone 《Microelectronic Engineering》2011,88(7):1079-1082
In this work, we present results of a study of anisotropic two-dimensional electron gas (2DEG) transport in N-polar GaN/AlGaN heterostructures grown on slightly mis-oriented sapphire substrates. High-resolution mobility spectrum analysis of magnetic-field dependent Hall-effect and resistivity indicate an isotropic 2DEG sheet carrier density, yet significant anisotropy was observed in carrier mobility. A single electron species with a narrow mobility distribution was found to be responsible for conduction parallel to the multi-atomic steps resulting from growth on the vicinal substrates; whilst in the perpendicular direction two distinct electrons peaks are evident at T ? 150 K, which merge near room temperature. The linewidth of the mobility distributions for transport in the perpendicular direction was found to be significantly broader than that of the single electron in the parallel direction. The broader mobility distribution and the lower average mobility for the 2DEG in the perpendicular direction are attributable to interface roughness scattering associated with the GaN/AlGaN interfacial steps. 相似文献
9.
G. A. Umana-Membreno H. Kala J. Antoszewski Z. H. Ye W. D. Hu R. J. Ding X. S. Chen W. Lu L. He J. M. Dell L. Faraone 《Journal of Electronic Materials》2013,42(11):3108-3113
We report results of a detailed study of electronic transport in n-on-p junctions formed by 150-keV boron-ion implantation in vacancy-doped p-type Hg0.769Cd0.231Te without postimplantation thermal annealing. A mobility spectrum analysis methodology in conjunction with a wet chemical etching-based surface removal approach has been employed to depth profile the transport characteristics of the samples. In the as-implanted samples, three distinct electron species were detected which are shown to be associated with (a) low-mobility electrons in the top 220-nm surface-damaged layer (E 1: μ 80K = 2940 cm2/Vs), (b) the B-ion implantation region in the top 500-nm region (E 2: μ 80K = 7490 cm2/Vs), and (c) high-mobility electrons in the n-to-p transition region at a depth of 600 nm to 700 nm (E 3: μ 80K = 25,640 cm2/Vs). Due to the maximum magnetic field employed (2 T), hole carriers from the underlying vacancy-doped p-type region were detected only after the removal of the top 220 nm of the profiled sample (μ 80K = 126 cm2/Vs), revealing fully p-type character 800 nm below the original sample surface. A comparison of the extracted E 2 electron concentration and calculated B-impurity profile suggests that the n-type region is due primarily to near-surface implantation-induced lattice damage. 相似文献
10.
G.A. Umana-Membreno G. Parish N. Fichtenbaum S. Keller U.K. Mishra B.D. Nener 《Journal of Electronic Materials》2008,37(5):569-572
Electrically active defects in n-GaN films grown with and without an Fe-doped buffer layer have been investigated using conventional and optical deep-level
transient spectroscopy (DLTS). Conventional DLTS revealed three well- defined electron traps with activation energies E
a of 0.21, 0.53, and 0.8 eV. The concentration of the 0.21 and 0.8 eV defects was found to be slightly higher in the sample
without the Fe-doped buffer, whereas the concentration of the 0.53 eV trap was higher in the sample with the Fe-doped buffer.
A minority carrier trap with E
a ≈ 0.65 eV was detected in both samples using optical DLTS; its concentration was ∼40% higher in the sample without the Fe-doped
buffer. Mobility spectrum analysis and multiple magnetic-field measurements revealed that the electron mobility in the topmost
layer of both samples was similar, but that the sample without the Fe-doped buffer layer was affected by parallel conduction
through underlying layers with lower electron mobility. 相似文献