Evidence for the occupation of DX centers in In0.29Al0.71As

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

1999

Articles you may be interested inGreen's function approach for transport calculation in a In 0.53 Ga 0.47 As/In 0.52 Al 0.48 As modulation-doped heterostructure Hole transport across the (Al,Ga)(As,Sb) barrier in InAs-(Al,Ga)(As,Sb) heterostructures Electrical transport properties of silicon delta-doped Al 0.30 Ga 0.70 As samples showing suppression of the DX center features Electrical and galvanomagnetic measurements, made on modulation ␦-doped-͑Si͒ Al 0.37 Ga 0.63 As/GaAs and In 0.34 Al 0.66 As/In 0.36 Ga 0.64 As heterostructures, fabricated into modulation doped field effect transistor-like gated Hall bars, were used to determine their DX center energies and densities in the normal and persistent photoconductive mode. Self-consistent Poisson/ Schrödinger simulations of the gate voltage dependence and of the temperature dependence of the charge transport parameters of these heterostructures provide the position of the Fermi levels in the barrier layers, E FB , relative to the conduction band minima and the electron densities in their quantum wells. The energy, E DX ϭ0.14 eV of Al 0.37 Ga 0.63 As determined from the temperature independent equilibrium position of E FB is consistent with the average of the three lowest DX center energies of this alloy. It is also consistent with that determined by others, on epitaxial Al 0.37 Ga 0.63 As layers, using conventional Hall measurement, deep level transient spectroscopic and hydrostatic pressure measurements. Strain relaxed In 0.34 Al 0.66 As/In 0.36 Ga 0.64 As heterostructures, grown on GaAs substrates, were used for similar measurements and simulations. These yield the energy of the DX centers in In 0.34 Al 0.66 As, relative to its ⌫-valley minimum, E DX ϭ0.18 eV. This value in conjunction with the previously determined DX center energies of AlAs and that of In 0.52 Al 0.48 As, above its conduction band edge, E DX (x) is correlated with, but not identical to, the composition dependence of the L band of In x Al 1Ϫx As.

Section: Introductionmentioning

confidence: 99%

DX centers in Al0.37Ga0.63As/GaAs and In0.34Al0.66As/In0.36Ga0.64As heterostructures

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

1999

“…However, to date there is significantly less work on DX centers in InxAll.xAs compounds. Young and Wieder [9] measured the DX center energy level in In 0 . 48 As on InP and partly because the energy level of the DX center is in resonance with the conduction band in In 0 .…”

Section: Introductionmentioning

confidence: 99%

DX Center Energy Level in In_xAl_1−xAs Compounds

1999

MRS Proc.

The presence of DX centers in InAll.xAs, primarily in the indirect portion of the In.All.-As bandgap, has been determined using modulation doped InAl 1 .×As/InyGa 1~y As heterostructures by means of persistent photoconductivity (PPC) and galvanomagnetic measurements. From the cooling bias experiment, the PPC, and self consistent Poisson and Schrddinger simulations the ratio of the ionized shallow donors to the DX centers is obtained. Using this ratio in the grand canonical ensemble (GCE) the energy level of DX centers is determined. It is found that the DX energy level merges with the conduction band at x_=0.42 and is resonant with the conduction band in higher indium concentration.

DX centers in InxAl1−xAs

Journal of Applied Physics

1999

The composition dependence of the energy levels of the DX centers in InxAl1−xAs/InyGa1−yAs heterostructures have been determined by means of Hall effect and persistent photoconductivity measurements made on gated Hall bar test structures, primarily in the indirect portion of the fundamental band gap of InxAl1−xAs. The energy of the DX center relative to the average of the main conduction band minima of the Brillouin zone, in the composition range, 0.1⩽x⩽0.34, is E(DX)∼0.3 eV; for x>0.4 the DX center is resonant with the conduction band.