Strain-Induced Reconstruction of Impurity States in PbTe(Ga) Films

1993 ◽  
Vol 308 ◽  
Author(s):  
Boris A. Akimov ◽  
Ludmila I. Ryabova ◽  
Evgeniy I. Slynko
Keyword(s):  
Electric Field ◽  
Cooling Rate ◽  
Carrier Concentration ◽  
Low Temperatures ◽  
Free Carrier ◽  
Rapid Decrease ◽  
Laser Deposition ◽  
Persistent Photoconductivity ◽  
Impurity States ◽  
Heating Up

ABSTRACTn-type PbTe(Ga) films were grown by the laser deposition and the hot wall techniques on BaF2 substrates in <111> orientation. Doping results in the appearance of a high-ohmic state with nearly intrinsic free carrier concentration at low temperatures and activation character of conductivity at T∼300 K. Persistent photoconductivity has been observed at T < 100 K. In the hot wall-grown layers a new effect of bistability during the cooling-heating-cooling cycles has been found. On the first stage of the cycle a rapid decrease of resistivity (∼3 orders of magnitude) is observed at To∼50 K. The value of To changes by ± 15 K depending on the cooling rate. After a brief heating up to 80 K the subsequent cooling results in the high-ohmic state of the layer at the low temperatures. This state seems to be unstable. Relaxation to the low ohmic state can be accelerated by the application of electric field. The effect may be understood in terms of bistability of the Ga impurity charge state under the action of strain between the film and the substrate during the cooling-down process.

Effect of Al Composition on the Deep Level Donors of AlxGa1-xSb/lnAs Single Quantum Wells

1992 ◽  
Vol 262 ◽  
Author(s):  
Irai Lo ◽  
W. C. Mitchel ◽  
C. E. Stutz ◽  
K. R. Evans ◽  
M. O. Manasreh
Keyword(s):  
Quantum Wells ◽  
Carrier Concentration ◽  
Electron Capture ◽  
Low Temperatures ◽  
Deep Level ◽  
Time Dependent ◽  
Universal Property ◽  
Persistent Photoconductivity ◽  
Single Quantum ◽  
Deep Donor

ABSTRACTWe have performed Shubnikov-de Haas (SdH) measurements on the AlxGa1-xSb/InAs QW's with x from 0.1 to 1.0 under the negative persistent photoconductivity (NPPC) conditions and confirmed the prediction of Ionized Deep Donor model that the NPPC effect is a universal property for the materials containing ionized deep donors at low temperatures. The time-dependent recombination (electron capture) of the ionized deep donors is similar to that of DX centers. The saturated reduction of carrier concentration in the InAs well increases with increasing x, and rises steeply at about x=0.4. The concentration of deep donors which cause the NPPC in the AlxGa1-xSb/InAs QW's increases with the Al composition.

scholarly journals Спектры остаточной фотопроводимости в гетероструктурах с квантовыми ямами HgTe/CdHgTe

2019 ◽  
Vol 53 (10) ◽  
pp. 1401
Author(s):  
К.Е. Спирин ◽  
Д.М. Гапонова ◽  
В.И. Гавриленко ◽  
Н.Н. Михайлов ◽  
С.А. Дворецкий
Keyword(s):  
Electric Field ◽  
Quantum Well ◽  
Carrier Concentration ◽  
Significant Role ◽  
General Trend ◽  
Persistent Photoconductivity ◽  
Free Carriers ◽  
Conductivity Type ◽  
P Type ◽  
Type Sample

Spectra of persistent photoconductivity (PPC) in HgTe/CdHgTe quantum well (QW) heterostructures of both n- and p-types have been investigated at T = 4.2 K. PPC is shown to be either positive (increase of carrier concentration in QW) or negative depending on a wavelength of the illumination. As a general trend, PPC maxima in n-type sample correspond to PPC minima in p-type samples and vice versa. It is discovered that in p-type samples the illumination with certain wavelengths results in the freezing out of free carriers in QWs but not in the conversion of the conductivity type. The latter indicates a significant role in the PPC mechanism of the built-in electric field that is switching off at the QW neutralization.

DX Centers in GaAs and AlxGal-x.As: Properties and Influence on Material and Device Characteristics

1987 ◽  
Vol 104 ◽  
Author(s):  
P. M. Mooney
Keyword(s):  
Low Temperature ◽  
Carrier Concentration ◽  
Conduction Band ◽  
Energy State ◽  
Free Carrier ◽  
Free Carrier Concentration ◽  
Persistent Photoconductivity ◽  
Dx Centers ◽  
Compensation Mechanisms ◽  
Dx Center

ABSTRACTThe DX center, the lowest energy state of the donor in AlGaAs with x > 0.22, is responsible for the reduced conductivity as well as the persistent photoconductivity observed in this material at low temperature. Extensive studies of the properties of this level and of its effects on the characteristics of some heterojunction devices are reviewed here. Recent measurements are presented showing that the characteristics of the DX center remain essentially unchanged when it is resonant with the conduction band (x < 0.22) and that, independent of other compensation mechanisms, the DX center therefore limits the free carrier concentration in GaAs to a maximum of about 2×1019 cm− 3.

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