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1.
The electrical properties of the ohmic contact systems Au/Pt/Ti/WSiN and Au/Pt/Ti to n+-InGaAs/GaAs layers grown by metalorganic vapor phase epitaxy were investigated and compared to each other. The thermal stability
properties of these contact systems were characterized by accelerated stress tests at elevated temperatures and by complementary
thin film x-ray diffraction analysis to evaluate the microstructural properties of degraded and nondegraded structures. The
goal of these efforts was to develop stable, homogeneous emitter contacts for power heterojunction bipolar transistors. It
was found that for both contact systems the best (specific) contact resistance Rc (ρ
c) is about 0.05 Ωmm (2 × 10−7 Ωcm2) in the as-deposited state. Au/Pt/Ti/WSiN contacts show no degradation after aging at 400°C for more than 20 h. This is in
contrast to standard Au/Pt/Ti contacts which significantly degrade even after short time annealing at 400°C. The good long-time
stability of the Au/Pt/Ti/WSiN system is related to the advantageous properties of the reactively sputtered WSiN barrier layer. 相似文献
2.
Excellent annealed ohmic contacts based on Ge/Ag/Ni metallization have been realized in a temperature range between 385 and 500/spl deg/C, with a minimum contact resistance of 0.06 /spl Omega//spl middot/mm and a specific contact resistivity of 2.62 /spl times/10/sup -7/ /spl Omega//spl middot/cm/sup 2/ obtained at an annealing temperature of 425/spl deg/C for 60 s in a rapid thermal annealing (RTA) system. Thermal storage tests at temperatures of 215 and 250/spl deg/C in a nitrogen ambient showed that the Ge/Ag/Ni based ohmic contacts with an overlay of Ti/Pt/Au had far superior thermal stabilities than the conventional annealed AuGe/Ni ohmic contacts for InAlAs/InGaAs high electron mobility transistors (HEMTs). During the storage test at 215/spl deg/C, the ohmic contacts showed no degradation after 200 h. At 250/spl deg/C, the contact resistance value of the Ge/Ag/Ni ohmic contact increased only to a value of 0.1 /spl Omega//spl middot/mm over a 250-h period. Depletion-mode HEMTs (D-HEMTs) with a gate length of 0.2 /spl mu/m fabricated using Ge/Ag/Ni ohmic contacts with an overlay of Ti/Pt/Au demonstrated excellent dc and RF characteristics. 相似文献
3.
A. A. Iliadis J. K. Zahurak T. Neal W. T. Masselink 《Journal of Electronic Materials》1999,28(8):944-948
We have investigated the formation of source-drain AuGe/Au and Ni/AuGe/Ni/Au alloyed ohmic contacts to AlInAs/InGaAs/InP doped
channel MODFETs, and observed lateral diffusion of the contact system after the standard annealing procedure at the temperature
range of 185 to 400°C. Auger depth profiling of contacts annealed at 250°C, revealed that Au(Ge) diffused through the top
InGaAs and AlInAs layers into the active InGaAs layer, but had reduced penetration into the AlInAs buffer layer. This reduction
in diffusion along the depth axis at the AlInAs buffer layer boundary is believed to result in enhanced lateral diffusion
and the observed lateral encroachment of the contacts. Both Au and Ni containing contact systems showed similar behavior in
terms of lateral diffusion with encroachment extending between 0.25 and 0.5 μm at the periphery of the contacts for annealing
temperatures between 300 and 400°C. A controlled ramp-to-peak temperature annealing procedure is developed to suppress such
lateral diffusion effects. Low temperature annealing (250°C) using this procedure resulted in equally low contact resistance
values (∼0.1Θ-mm) and no lateral diffusion. It is concluded that in thin multilayered structures the modified annealing procedure
presented here, is necessary for optimal ohmic contact formation. 相似文献
4.
5.
P型GaAs欧姆接触的制作 总被引:2,自引:0,他引:2
在以Be作为离子源离子注入形成的P型GaAs衬底上分别使用Ti/Pt/Au和Cr/Pt/Au多层金属作为欧姆接触金属,并对比合金前后的差别。结果表明,使用Ti/Pt/Au作为欧姆接触金属效果更好,合金对于降低欧姆接触电阻率效果明显,合金后Ti/Pt/Au的接触电阻率可达到3.08×10-5Ω.cm2。 相似文献
6.
Dae-Woo Kim Hee-Soo Park Joon Seop Kwak Hong Koo Baik Sung-Man Lee 《Journal of Electronic Materials》1999,28(8):939-943
The ohmic contact formation mechanism and the role of Pt layer of Au(500Å) Pt(500Å)/Pd(100Å) ohmic contact to p-ZnTe were investigated. The specific contact resistance of Au/Pt/Pd contact depended strongly on the annealing temperature. As the annealing temperature increased, the specific contact resistance decreased and reached a minimum value of 6×10?6 Θcm2 at 200°C. From the Hall measurement, the hole concentration increased with the annealing temperature and reached a maximum value of 2.3×1019 cm?3 at 300°C. The Schottky barrier height decreased with the increase of annealing temperature and reached a minimum value of 0.34 eV at 200°C and it was due to the interfacial reaction of Pd and ZnTe. Therefore, the decrease of contact resistance was due to the increase of doping concentration as well as the decrease of Schottky barrier height by the interfacial reaction of Pd ZnTe. The specific contact resistances of Au Pd, Au/Pt/Pd and Au/Mo/Pd as a function of annealing time was investigated to clarify the role of Pt layer. 相似文献
7.
Y. C. Lin Sheng-Li Shie Tin-En Shie Yuen-Yee Wong K. S. Chen E. Y. Chang 《Journal of Electronic Materials》2011,40(3):289-294
This study investigates electrical characteristics and the formation mechanism of the Cu/Ge/Pd Ohmic contact to n-type InGaAs. After annealing the contact at 250°C for 20 min, Cu3Ge and Pd12Ga5As2 compounds formed and Ge diffused into the InGaAs layer, achieving a heavily doped InGaAs layer with a low contact resistivity
of 1 × 10−6 Ω cm2. Thermal stability tests were performed on the Cu/Ge/Pd Ohmic contact to InGaAs after Ohmic contact formation, showing no
obvious degradation after a 72 h reliability test at 250°C. The results indicate excellent electrical characteristics and
thermal stability using Cu/Ge/Pd as an Ohmic contact metal to an n-InGaAs layer. 相似文献
8.
We report the effect of the Pt barrier on the thermal stability of Ti/Al/Pt/Au in ohmic contact with Si-implanted n-type GaN
layers. Ti/Al/Au (25/100/200 nm) and Ti/Al/Pt/Au (25/100/50/200 nm) multilayers were, respectively, deposited on as-implanted
and recovered Si-implanted n-type GaN samples. The associated dependence of the specific contact resistance on the annealing
time at various temperatures was compared. The long-term ohmic stability of a Ti/Al/Pt/Au multilayer in contact with a Si-implanted
n-type GaN layer was much better than that of the Ti/Al/Au multilayer. This superior stability is attributed to the barrier
function of the Pt interlayer. The Pt/Au bilayer can also passivate the propensity of oxidation for the conventional Ti/Al
bilayer in contact with n-type GaN layers at elevated temperatures. 相似文献
9.
Ni/Ag/Ti/Au金属系反射镜电极广泛用于GaN基垂直结构发光二极管(LED)的传统制造工艺.这种电极需要进行高温长时间整体退火才能获得高质量的欧姆接触,但对电极的反射率和器件性能影响较大.介绍了一种新工艺方法,该方法将电极分解为接触层和反射层,降低反射层经历的退火温度和时间,获得了拥有良好的欧姆接触特性和高反射率的反射镜电极,解决了传统电极光学性能和电学性能相互制约的问题.首先生长极薄的Ni/Ag作为接触层,对接触层进行高温长时间退火后再生长厚层Ag作为反射层,之后再进行一次低温退火.使得对反射起主要作用的反射层免于高温长时间退火,相较于传统Ni/Ag/Ti/Au电极,该方法在获得更优良的欧姆接触的同时,提升了电极的反射率.在氧气氛围下进行500℃接触层退火3 min,400℃整体退火1 min后,电极的比接触电阻率为1.7×l0-3Ω·cm2,同时在450 nm处反射率为93%. 相似文献
10.
基于圆形传输线模型,研究了背景载流子浓度为71016cm3的非故意掺杂GaN与Ti/Al/Ni/Au多层金属之间欧姆接触的形成。样品在N2气氛中,分别经过温度450,550,700,800,900℃的1 min快速热退火处理后发现,当退火温度高于700℃欧姆接触开始形成,随着温度升高欧姆接触电阻持续下降,在900℃时获得了最低比接触电阻6.6106O·cm2。研究表明,要获得低的欧姆接触电阻,需要Al与Ti发生充分固相反应,并穿透Ti层到达GaN表面;同时,GaN中N外扩散到金属中,在GaN表面产生N空位起施主作用,可提高界面掺杂浓度,从而有助于电子隧穿界面而形成良好欧姆接触。 相似文献
11.
Si上外延的n型3C-SiC欧姆接触研究 总被引:2,自引:0,他引:2
用LPCVD在Si(111)上异质外延了n型3C-SiC,并在所外延的3C-SiC上蒸发Au/Ti,通过不同温度下的RTA(快速热退火)形成欧姆接触。用两种不同的传输线模型对Ti/3C-SiC欧姆接触的ρc(比接触电阻率)进行测量,在750°C退火后Ti/3C-SiC的ρc达到了最低值为3.68×10-5Ω·cm2,这满足了应用的要求。AES分析结果还表明由于Ti的氧化,更高温度下的退火会使ρc增大。 相似文献
12.
13.
For the first time in Russia, the Si/Al/Ti/Au alloyed contact composition is investigated for the formation of ohmic contacts to AlGaN/GaN heterostructures using thermal annealing. The obtained results are compared with those for conventional Ti/Al/Ni/Au ohmic contacts. Use of the composition under investigation makes it possible to decrease the annealing temperature to 675–700°C, which results in improvement in the morphology of alloyed ohmic contacts in comparison with conventional contacts. The value of the contact resistance using the Si/Al-based composition to the AlGaN/GaN heterostructure is obtained in relation to the temperature and annealing duration. It is shown that no qualitative change in the resistance occurs at an annealing duration of several minutes in the temperature range of 700–750°C. In the temperature range of 675–700°C, there is an asymptotic decrease in the contact resistance with increasing annealing duration. The smallest value of the contact resistance amounts to 0.41 Ω mm. 相似文献
14.
The aim of this study is to improve the electrical properties of ohmic contacts that plays crucial role on the performance of optoelectronic devices such as laser diodes (LDs), light emitting diodes (LEDs) and photodetectors (PDs). The conventional (Pd/Ir/Au, Ti/Pt/Au and Pt/Ti/Pt/Au), Au and non-Au based rare earth metal-silicide ohmic contacts (Gd/Si/Ti/Au, Gd/Si/Pt/Au and Gd/Si/Pt) to p-InGaAs were investigated and compared each other. To calculate the specific contact resistivities the Transmission Line Model (TLM) was used. Minimum specific contact resistivity of the conventional contacts was found as 0.111 × 10−6 Ω cm2 for Pt/Ti/Pt/Au contact at 400 °C annealing temperature. For the rare earth metal-silicide ohmic contacts, the non-Au based Gd/Si/Pt has the minimum value of 4.410 × 10−6 Ω cm2 at 300 °C annealing temperature. As a result, non-Au based Gd/Si/Pt contact shows the best ohmic contact behavior at a relatively low annealing temperature among the rare earth metal-silicide ohmic contacts. Although the Au based conventional ohmic contacts are thermally stable and have lower noise in electronic circuits, by using the non-Au based rare earth metal-silicide ohmic contacts may overcome the problems of Au-based ohmic contacts such as higher cost, poorer reliability, weaker thermal stability, and the device degradation due to relatively higher alloying temperatures. To the best of our knowledge, the Au and non-Au based rare earth metal-silicide (GdSix) ohmic contacts to p-InGaAs have been proposed for the first time. 相似文献
15.
16.
应用Au/Ge/Ni系金属在InAlAs/InGaAs/InP HEMT上成功制作了良好的合金欧姆接触。采用WN和Ti双扩散阻挡层工艺优化欧姆接触,在样品上获得了最低9.01×10-8Ω.cm2的比接触电阻,对应的欧姆接触电阻为0.029Ω.mm。同时,在模拟后续工艺环境的20min250°C热处理后,器件的欧姆接触性能无显著变化,表明其具有一定的温度稳定性。 相似文献
17.
B. Boudart S. Trassaert X. Wallart J. C. Pesant O. Yaradou D. Théron Y. Crosnier H. Lahreche F. Omnes 《Journal of Electronic Materials》2000,29(5):603-606
We report a comparison between Ti/Al and Ti/Al/Ni/Au ohmic contacts in terms of contact resistivity, thermal stability, depth
profile, and surface morphology. The metals were deposited by conventional electron-beam evaporation, and then annealed at
900°C for 30 s in a N2 atmosphere. The lowest value for the specific contact resistivity was obtained using Ti/Al/Ni/Au metallization. Ti/Al/Ni/Au
contacts showed no increase in contact resistivity after aging for five days at 600°C in an air atmosphere. Examination of
the surface morphology using atomic force microscopy revealed that the surface roughness was clearly better in the case of
Ti/Al/Ni/Au contacts. X-ray photoelectron spectroscopy was also employed and gave primary results of Ti/Al/Ni/Au contact formation. 相似文献
18.
The metallurgical stability of ohmic contacts: Pt, Pt/Ti, Au/Ti, Au/Pt/Ti, and Au/Pt/Ti/W, on a 500 Å thick p+-InGaAs base of InP/InGaAs/InP HBTs have been investigated as a function of anneal temperature. All contacts were stable after a 300°C-30 s anneal. Pt contact failed at 350°C whereas Pt/Ti, Au/Ti, and Au/Pt/Ti contacts failed at 400°C. The failure mechanism was a collector leakage short owing to the penetration of Pt or Ti through the thin base. Only HBTs with Au/Pt/Ti/W contact were still functional after a 400°C anneal with no apparent shift in the turn-on voltage for the emitter and collector junctions 相似文献
19.
Ping Jian Douglas G. Ivey Robert Bruce Gordon Knight 《Journal of Electronic Materials》1994,23(9):953-962
Two Pd-based metallizations have been systematically studied, i.e., Au/Ge/Pd and Pd/Ge contacts to n-type InP, in an attempt
to better understand the role of the metallization constituents in forming ohmic contacts. Ohmic contacts were obtained with
minimum specific resistances of 2.5 × 10−6 Ω-cm2 and 4.2 × 10−6 Ω-cm2 for the Au/Ge/Pd and the Pd/Ge contacts, respectively. The annealing regime for ohmic contact formation is 300-375°C for
the Au/Ge/Pd/InP system and 350-450°C for the Pd/GelnP system. Palladium, in both cases, reacts with InP to form an amorphous
layer and then an epitaxial layer at low temperatures, providing good metallization adhesion to InP substrates and improved
contact morphology. Ohmic contact formation in both contacts is attributed to Ge doping, based on the solid state reaction-driven
decomposition of an epitaxial layer at the metallization/InP interface, producing a very thin, heavily doped InP layer. Gold
appears to be responsible for the difference in contact resistance in the two systems. It is postulated that Au reacts strongly
with In to form Au-In compounds, creating additional In site vacancies in the InP surface region (relative to the Au-free
metallization), thereby enhancing Ge doping of the InP surface and lowering the contact resistance. Both contacts degrade
and ultimately become Schottky barriers again if over annealed, due to consumption of additional InP, which destroys the heavily
doped InP layer. 相似文献
20.
Kartika Chandra Sahoo Chun-Wei Chang Yuen-Yee Wong Tung-Ling Hsieh Edward Yi Chang Ching-Ting Lee 《Journal of Electronic Materials》2008,37(6):901-904
The thermal stability of the Cu/Cr/Ge/Pd/n+-GaAs contact structure was evaluated. In this structure, a thin 40 nm layer of chromium was deposited as a diffusion barrier
to block copper diffusion into GaAs. After thermal annealing at 350°C, the specific contact resistance of the copper-based
ohmic contact Cu/Cr/Ge/Pd was measured to be (5.1 ± 0.6) × 10−7 Ω cm2. Diffusion behaviors of these films at different annealing temperatures were characterized by metal sheet resistance, X-ray
diffraction data, Auger electron spectroscopy, and transmission electron microscopy. The Cu/Cr/Ge/Pd contact structure was
very stable after 350°C annealing. However, after 400°C annealing, the reaction of copper with the underlying layers started
to occur and formed Cu3Ga, Cu3As, Cu9Ga4, and Ge3Cu phases due to interfacial instability and copper diffusion. 相似文献