DEPENDENCE OF CAPACITANCE–VOLTAGE CHARACTERISTICS OF NOMINALLY UNDOPED AlGaN/GaN HETEROSTRUCTURES ON SEVERAL KEY PARAMETERS OF THE MATERIALS

2011 ◽  
Vol 25 (15) ◽  
pp. 1293-1302 ◽  
Author(s):  
GUIYING TAN ◽  
YONGBO SU
Keyword(s):  
Barrier Layer ◽  
Chemical Vapor ◽  
Thickness Effect ◽  
Organic Chemical ◽  
Carrier Distribution ◽  
Al Content ◽  
Algan Barrier ◽  
Capacitance Voltage ◽  
Algan Barrier Layer ◽  
Gan Heterostructure

Nominally undoped AlGaN / GaN heterostructure samples were grown on c-plane sapphire substrates by low-pressure metal-organic chemical vapor deposition, and their material properties, such as crystal quality, roughness of heterointerface, thickness and Al mole fraction of AlGaN barrier layer, were identified by high resolution X-ray diffraction (HRXRD). Mercury-probe capacitance–voltage (C–V) measurements were carried out to investigate the carrier distribution in the heterostructures and accurately evaluate the sheet carrier concentration of two-dimensional electron gas (2DEG) formed at AlGaN / GaN heterointerface. The dependence of C–V characteristics of these samples on some key material parameters were clearly revealed. The Al -content effect, barrier-thickness effect in AlGaN layer, and their synergy effect were specifically studied. It demonstrated that the C–V characteristics of AlGaN / GaN heterostructure could be improved by perfecting the crystal epitaxial process, and adjusting the Al -content or thickness of AlGaN barrier layer.

Impact of strain relaxation of AlGaN barrier layer on the performance of high Al-content AlGaN/GaN HEMT

2006 ◽  
Vol 49 (4) ◽  
pp. 393-399 ◽  
Author(s):  
Yan Yang ◽  
Yue Hao ◽  
Jincheng Zhang ◽  
Chong Wang ◽  
Qian Feng
Keyword(s):  
Barrier Layer ◽  
Strain Relaxation ◽  
Al Content ◽  
Gan Hemt ◽  
Algan Barrier ◽  
Algan Barrier Layer ◽  
High Al Content

AlGaN/GaN Heterostructure Field-Effect Transistors with Back-Doping Design for High-Power Applications: High Current Density with High Transconductance Characteristics

2002 ◽  
Vol 743 ◽  
Author(s):  
Narihiko Maeda ◽  
Kotaro Tsubaki ◽  
Tadashi Saitoh ◽  
Takehiko Tawara ◽  
Naoki Kobayashi
Keyword(s):  
Barrier Layer ◽  
Field Effect ◽  
Field Effect Transistors ◽  
High Current Density ◽  
High Current ◽  
Algan Barrier ◽  
Heterostructure Field Effect Transistors ◽  
Algan Barrier Layer ◽  
Gan Heterostructure ◽  
High Transconductance

ABSTRACTElectron transport properties and DC device characteristics have been examined in the AlGaN/GaN heterostructure field-effect transistors (HFETs) with back-doping design that makes it possible to obtain high two-dimensional electron gas (2DEG) densities even for the devices with thin AlGaN barrier layers. In the back-doping design, an asymmetric double-heterostructure is employed, and donor atoms are doped not only in the surface-side AlGaN layer but also in the underlying AlGaN layer. In this structure, electrons are efficiently supplied also from the back-doped AlGaN barrier layer to the GaN channel and merged into a single 2DEG layer, with the help of the negative polarization charges at the heterointerface between the GaN channel and the underlying AlGaN barrier layer. By using back-doping design, very high 2DEG densities around 3×1013 cm−2 has been achieved in the Al0.3Ga0.7N/GaN HFET whose barrier layer (Al0.3Ga0.7N) is designed to be as thin as 120 Å. An HFET with the gate-length of 1.5 μm has exhibited a high current density of 1.2 A/mm and a high transconductance of 200 mS/mm, which is ascribed to high 2DEG densities and thin barrier layers in these devices. HFETs with the back-doping design are thus promising for high-power applications.

Influence of thermal stress on the relative permittivity of the AlGaN barrier layer in an AlGaN/GaN heterostructure Schottky contacts

2011 ◽  
Vol 20 (9) ◽  
pp. 097106 ◽  
Author(s):  
Yuan-Jie Lü ◽  
Zhao-Jun Lin ◽  
Yu Zhang ◽  
Ling-Guo Meng ◽  
Zhi-Fang Cao ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Barrier Layer ◽  
Relative Permittivity ◽  
Schottky Contacts ◽  
Algan Barrier ◽  
Algan Barrier Layer ◽  
Gan Heterostructure

Back-Doping Design in AlGaN/GaN Heterostructure Field-Effect Transistors for High-Power Applications

2001 ◽  
Vol 693 ◽  
Author(s):  
Narihiko Maeda ◽  
Kotaro Tsubaki ◽  
Tadashi Saitoh ◽  
Naoki Kobayashi
Keyword(s):  
Barrier Layer ◽  
High Power ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Algan Layer ◽  
Barrier Layers ◽  
Algan Barrier ◽  
Heterostructure Field Effect Transistors ◽  
Algan Barrier Layer ◽  
Gan Heterostructure

AbstractA novel doping design has been proposed that yields high two-dimensional electron gas (2DEG) densities in the AlGaN/GaN heterostructure field-effect transistors (HFETs) even when the AlGaN barrier layers are designed to be very thin. In the novel doping design, an asymmetric double-heterostructure is employed, and donor atoms are doped not only in the surface-side AlGaN layer but also in the underlying AlGaN layer. In this structure, electrons are efficiently supplied also from the back-doped AlGaN barrier layer to the GaN channel, with the help of the negative polarization charges at the heterointerface between the GaN channel and the underlying AlGaN barrier layer. High 2DEG densities can thus be obtained. Moreover, relatively high 2DEG mobilities can be obtained for high 2DEG densities, because back-doped donor atoms are sufficiently remote from the position of the 2DEG so that the 2DEG is less subjected to the ionized impurity scattering due to the relevant donor atoms. By using this back-doping design, a very high 2DEG density of 2.8x1013 cm-2 (2DEG mobility is 850 cm2/Vs) has been obtained at 300 K in the Al0.3Ga0.7N/GaN HFET whose barrier layer (Al0.3Ga0.7N) is as thin as 120 Å. Thus, the back-doping design is effective to obtain high 2DEG densities in the HFETs with thin barrier layers, and promising for high-power applications.

High Barrier Height n-GaN Schottky diodes with a barrier height of 1.3 eV by using sputtered copper metal

1999 ◽  
Vol 572 ◽  
Author(s):  
W. C. Lai ◽  
M. Yokoyama ◽  
C. Y. Chang ◽  
J. D. Guo ◽  
J. S. Tsang ◽  
...  
Keyword(s):  
Barrier Height ◽  
Vapor Deposition ◽  
Schottky Diodes ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Copper Metal ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

ABSTRACTCopper Schottky diodes on n-type GaN grown by metal-organic chemical vapor deposition were achieved and investigated. Ti/Al was used as the ohmic contact. The copper metal is deposited by the Sputter system. The barrier height was determined to be as high as (ΦB =1.13eV by current-voltage (I-V) method and corrected to be ΦB =1.35eV as considered the ideality factor, n, with the value of 1.2. By the capacitance-voltage (C-V) method, the barrier height is determined to be ΦB =1.41eV. Both results indicate that the sputtered copper metal is a high barrier height Schottky metal for n-type GaN.

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