Contactless Electromodulation Characterization of Compound Semiconductor Surfaces and Device Structures

1993 ◽  
Vol 324 ◽  
Author(s):  
J.M. Woodall
Keyword(s):  
Fermi Level ◽  
Electric Fields ◽  
Growth Conditions ◽  
Compound Semiconductor ◽  
Conduction Band Edge ◽  
Semiconductor Surfaces ◽  
Air Exposure ◽  
Fermi Level Pinning ◽  
Characterization Of Properties

AbstractThis paper will review the use of contactless electromodulation methods, such as photoreflectance (PR) and contactless electroreflectance (CER), to characterize the electronic properties of compound semiconductor surfaces exposed to different growth and post-growth conditions. Also the characterization of properties critical to device performance can be evaluated. For example, using PR and CER it has been found that there is a lower density of surface hole traps than electron traps in certain as-grown MBE (001) GaAs samples and that this condition persists even after air exposure. This behaviour is in contrast to other samples, including both bulk and MBE grown (001) surfaces in which the Fermi level is pinned mid-gap for both n- and p-type structures. We also have observed that Ar+ bombardment under UHV conditions results in Fermi level pinning close to the conduction band edge and that thermal annealing restores mid-gap pinning. Finally, using PR we are able to characterize the electric fields and associated doping levels in the emitter and collector regions of heterojunction bipolar transistor structures (fabricated from III-V materials), thus demonstrating the ability to perform inprocess evaluation of important device parameters.

NEGATIVE MAGNETORESISTANCE IN PbTe(Mn,Cr)

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3343-3346 ◽  
Author(s):  
D. KHOKHLOV ◽  
I. IVANCHIK ◽  
A. KOZHANOV ◽  
A. MOROZOV ◽  
E. SLYNKO ◽  
...  
Keyword(s):  
Fermi Level ◽  
Band Edge ◽  
Negative Magnetoresistance ◽  
Conduction Band Edge ◽  
Valence Band Edge ◽  
Narrow Gap ◽  
Magnetoresistance Effect ◽  
Fermi Level Pinning ◽  
P Type ◽  
Substantial Drop

We have observed the negative magnetoresistance effect in the narrow-gap PbTe(Mn,Cr) semiconductor, in which the Fermi level is pinned within the gap nearby the conduction band edge. Previously the giant negative magentoresistance effect has been reported in PbTe(Mn,Yb), in which the Fermi level is pinned in the gap nearby the valence band edge. It is known that in the case of Yb doping the Fermi level pinning results from the 2+ - 3+ valence instability of an impurity. The same sort of the valence instability provides the Fermi level pinning in PbTe(Mn,Cr), but the conductivity is of the n-type, not of the p-type as in PbTe(Mn,Yb). Introduction of magnetic field leads to substantial drop of the PbTe(Mn,Cr) resistivity of about 30% at T = 4.2 K. This is however much lower than in PbTe(Mn,Yb), where the effect amplitude reached 3 orders of magnitude. The effect disappears at T = 15 K. Possible mechanisms of the effect are discussed.

Tomographic investigation of fermi level pinning at focused ion beam milled semiconductor surfaces

2013 ◽  
Vol 103 (26) ◽  
pp. 264104 ◽  
Author(s):  
D. Wolf ◽  
A. Lubk ◽  
A. Lenk ◽  
S. Sturm ◽  
H. Lichte
Keyword(s):  
Fermi Level ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Semiconductor Surfaces ◽  
Fermi Level Pinning

The Effect of Mn Concentration on Curie Temperature and Magnetic Behavior of MOCVD Grown GaMnN Films

2004 ◽  
Vol 834 ◽  
Author(s):  
Erkan Acar Berkman ◽  
Mason J. Reed ◽  
F. Erdem Arkun ◽  
Nadia A. El-Masry ◽  
John M. Zavada ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Fermi Level ◽  
Solid Solutions ◽  
Room Temperature ◽  
Growth Conditions ◽  
Ferromagnetic Behavior ◽  
Secondary Phases ◽  
Mn Doping ◽  
Mn Concentration

ABSTRACTWe report on the growth and characterization of dilute magnetic semiconductor GaMnN showing ferromagnetism behavior above room temperature. GaMnN films were grown by MOCVD using (EtCp2)Mn as the precursor for in-situ Mn doping. Structural characterization of the GaMnN films was achieved by XRD, SIMS and TEM measurements. XRD and TEM confirmed that the films were single crystal solid solutions without the presence of secondary phases. SIMS analysis verified that Mn was incorporated homogeneously throughout the GaMnN layer which was ∼0.7μm thick. Ferromagnetic behavior for these films was observed along the c-direction (out of plane orientation) in a Mn concentration range of 0.025–2%. The saturation magnetization ranged from 0.18–1.05 emu/cc for different growth conditions. Curie temperatures of the GaMnN films were determined to be from 270 to above 400K depending on the Mn concentration. This dependence of Curie temperature on concentration of Mn in GaMnN indicates that the grown films are random solid solutions. SQUID measurements ruled out the possibility of spin-glass and superparamagnetism in these MOCVD grown GaMnN films. The grown films were electrically semi-insulating; however PL measurements showed that the films were still optically active after Mn doping. This study showed that the growth of III-Nitride films doped with Mn requires a small window of growth conditions that depend on growth temperature and (EtCp)2Mn flux to achieve ferromagnetism above room temperature, and the magnetic response of the film depends on the Fermi level position. We suggest that ferromagnetism occurs when the Fermi level lies within the Mn energy level which is 1.4 eV above the GaN valence band.

Role of an interlayer at a TiN/Ge contact to alleviate the intrinsic Fermi-level pinning position toward the conduction band edge

2014 ◽  
Vol 104 (13) ◽  
pp. 132109 ◽  
Author(s):  
Keisuke Yamamoto ◽  
Masatoshi Mitsuhara ◽  
Keisuke Hiidome ◽  
Ryutaro Noguchi ◽  
Minoru Nishida ◽  
...  
Keyword(s):  
Fermi Level ◽  
Conduction Band ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Fermi Level Pinning
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