Improved Mobilities and Resistivities in Modulation-Doped P-type AlGaN / GaN Superlattices

2001 ◽  
Vol 693 ◽  
Author(s):  
Erik L. Waldron ◽  
John W. Graff ◽  
E. Fred Schubert ◽  
Amir M. Dabiran
Keyword(s):  
Standard Sample ◽  
Variable Temperature ◽  
Impurity Scattering ◽  
Two Dimensional ◽  
Polarization Effects ◽  
Ionized Impurity Scattering ◽  
Capacitance Voltage ◽  
Superlattice Structures ◽  
P Type ◽  
Mg Doped

AbstractP-type AlGaN / GaN superlattice structures have demonstrated higher acceptor activation due to a modulated valence band resulting from the superlattice as well as spontaneous and piezoelectric polarization fields. The polarization effects are due to the wurtzite structure of AlGaN and the strain present in AlxGa1-xN / GaN heterostructures. Variable temperature Hall effect studies of Mg doped Al0.20Ga0.80N / GaN superlattices reveal an improvement in resistivity and mobility for modulation-doped structures versus uniformly doped structures. Very low resistivities less than 0.1 & cm and hole mobilities ~ 36 cm2/V s are demonstrated. This improvement is attributed to a reduction of neutral and ionized impurity scattering for the two-dimensional hole gas present in the GaN layers of the modulation-doped superlattice. The improvement is greatest at temperatures below ~ 150 K. The doped regions of the superlattices have Mg concentrations of ~1019 cm-3. Two modulation-doped samples were grown by MBE: a standard scheme with dopants only in the AlGaN barriers, and a shifted scheme with dopants concentrated near the AlGaN / GaN interfaces. The standard sample has mobilities of 8.9 and 36 cm2/V s at 300 and 90 K, respectively. Resistivities of the standard sample are 0.21 and 0.068 Ω cm at 300 and 90 K, respectively. Carrier concentrations for this sample are 3.4 and 2.5 x 1018 cm-3 at 300 and 90 K, respectively. Capacitance-voltage profiling on the samples shows a clear indication of a two-dimensional hole gas as well as the periodicity of the superlattice.

scholarly journals Improvement of p-Type AlGaN Conductivity with an Alternating Mg-Doped/Un-Doped AlGaN Layer Structure

Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 835
Author(s):  
Chi-Chung Chen ◽  
Yu-Ren Lin ◽  
Yu-Wei Lin ◽  
Yu-Cheng Su ◽  
Chung-Chi Chen ◽  
...  
Keyword(s):  
Sheet Resistance ◽  
Layer Structure ◽  
Reference Sample ◽  
Impurity Scattering ◽  
Hole Mobility ◽  
Al Content ◽  
Ionized Impurity Scattering ◽  
Layer Structures ◽  
P Type ◽  
Mg Doped

Using molecular beam epitaxy, we prepared seven p-type AlGaN samples of ~25% in Al content, including six samples with Mg-doped/un-doped AlGaN alternating-layer structures of different layer-thickness combinations, for comparing their p-type performances. Lower sheet resistance and higher effective hole mobility are obtained in a layer-structured sample, when compared with the reference sample of uniform Mg doping. The improved p-type performance in a layer-structured sample is attributed to the diffusion of holes generated in an Mg-doped layer into the neighboring un-doped layers, in which hole mobility is significantly higher because of weak ionized impurity scattering. Among the layer-structured samples, that of 6/4 nm in Mg-doped/un-doped thickness results in the lowest sheet resistance (the highest effective hole mobility), which is 4.83 times lower (4.57 times higher) when compared with the sample of uniform doping. The effects of the Mg-doped/un-doped layer structure on p-type performance in AlGaN and GaN are compared.

Mobility characterization of p-type and n-type strained sil-x-yGexcy/Si Epilayer hall devices

1998 ◽  
Vol 535 ◽  
Author(s):  
Jeff J. Petersoa ◽  
Charles E. Hunt ◽  
Stefan F. Zappe ◽  
Ernst Obeneier ◽  
Richard Westhoff ◽  
...  
Keyword(s):  
Doping Level ◽  
Doping Concentration ◽  
Impurity Scattering ◽  
Temperature Range ◽  
Boron Doped ◽  
Ionized Impurity Scattering ◽  
Van Der Pauw ◽  
P Type

AbstractMobilities in Si1-x-yGex Cy layers were measured using mesa etched Van der Pauw structures for alloy layers with 0 < x < 0.30 and 0 < y < 0.02 and doping levels of 1015 < N < 1018 cm-3. Mobilities in Si1-x-yGex Cy layers with x = 0.27 were found to approach Si mobilities for both μn and μp.While electron mobilities in phosphorous-doped SiGeC decrease with doping concentration, hole mobilities in boron-doped SiGeC increase with doping level, indicating ionized impurity scattering is not dominant for μp over the temperature range studied.

Ionized impurity scattering in heavily doped p-type InSb thin films

1979 ◽  
Vol 60 (2) ◽  
pp. 249-255 ◽  
Author(s):  
K.V. Krishna ◽  
P.C. Mathur ◽  
A.L. Dawar ◽  
O.P. Taneja
Keyword(s):  
Thin Films ◽  
Impurity Scattering ◽  
Ionized Impurity Scattering ◽  
Insb Thin Films ◽  
Heavily Doped ◽  
P Type

Photoluminescence, Capacitance-Voltage, and Variable Field Hall Effect Measurements of Mg-Doped InN

2006 ◽  
Vol 955 ◽  
Author(s):  
Craig Hartley Swartz ◽  
Steven M. Durbin ◽  
Roger J. Reeves ◽  
Katherine Prince ◽  
John V. Kennedy ◽  
...  
Keyword(s):  
Hall Effect ◽  
Molecular Beam ◽  
Variable Magnetic Field ◽  
Surface Electron ◽  
Type Layer ◽  
Capacitance Voltage ◽  
Hall Effect Measurements ◽  
P Type ◽  
Lattice Matched ◽  
Mg Doped

ABSTRACTVariable magnetic field Hall effect, photoluminescence (PL) and capacitance-voltage (CV) analysis have been used to study InN layers grown by plasma assisted molecular beam epitaxy. All three techniques reveal evidence of a buried p-type layer beneath a surface electron accumulation layer in heavily Mg-doped samples. The use of lattice-matched Yttria-stablized Zirconia substrates also provides evidence of a p-type layer.

Doping-induced contrast in secondary electron images of silicon

1994 ◽  
Vol 52 ◽  
pp. 1024-1025
Author(s):  
David Venables ◽  
Dennis M. Maher
Keyword(s):  
Integrated Circuits ◽  
Secondary Electron ◽  
Lateral Diffusion ◽  
Experimental Information ◽  
Two Dimensional ◽  
Vertical Diffusion ◽  
Band Bending ◽  
The Difference ◽  
Superlattice Structures ◽  
P Type

As device dimensions in integrated circuits continue to decrease to dimensions on the order of 0. 1μm, obtaining two dimensional maps of the dopant distribution becomes increasingly important. In particular, process simulators attempt to predict the extent of both lateral and vertical diffusion of the dopants. However, experimental information on lateral diffusion has been difficult to obtain, although a variety of techniques based on microscopic and electrical data have been attempted. Recently, Perovic et al. showed that direct secondary electron (SE) images of n-i-p-i superlattice structures in Si could be obtained in a field-emission scanning electron microscope (FESEM). They suggested that this “electronic contrast” was due to the difference in band-bending behavior between n and p-type materials at the specimen surface. In this paper, we show that this phenomenon can be exploited to reveal direct two dimensional images of the extent of lateral and vertical diffusion of dopants in patterned silicon wafers. In addition, we show that the contrast exhibited by the doped regions is a strong function of electron beam energy.

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