Electrical Properties of InGaP Doped with Si

We measured Hall concentration n in InGaP:Si epitaxial layers grown by MBE as a function of pressure P up to 2 GPa and of temperature T from 77 to 300 K. We interpreted our results in terms of the broad distribution of impurity states resonant with the conduction band. From the low-temperature n(P) dependence we can directly obtain the total density of impurity states around the Fermi level ρ(E$\text{}_{F}$). The Fermi level can be shifted with respect to impurity states by applying pressure and by using samples with different n. In this way we obtain ρ(E) in a wide energy range. We discuss the possible reasons for the observed broad distribution of ρ(E)

Universal Behaviour of Magnetoconductance due to Weak Localization in Two-Dimensional Systems - Example of GaInAs Quantum Wells

Weak localization corrections to conductivity of a two-dimensional electron gas are studied by measurements of the magnetic field dependence of the conductivity in GalnAs quantum wells. We observe that, when presented as a function of the normalized magnetic field (x = B/B$\text{}_{tr}$, where B is the magnetic field, B$\text{}_{tr}$ = ħ/4eτD, D is the diffusion constant and τ is momentum relaxation time), different samples show very similar high field behaviour. A theoretical description is developed that allows one to describe in a consistent way high and low field behaviour. The theory predicts universal (B$\text{}^{1}\text{}^{/}\text{}^{2}$) behaviour of the conductivity correction for all 2D systems in the high field limit (r > 1). Low field behaviour depends strongly on spin and phase relaxation mechanisms. Comparison of the theory with experiment confirms the universal behaviour in the high field limit and allows one to estimate the spin and phase relaxation times for different GaInAs quantum wells

Lattice Constant of Doped Semiconductor

The paper shows an influence of doping on lattice constant of a semiconductor. Three effects are discussed: (i) "size" effect caused by a different ionic radii of dopant and host atoms, (ii) lattice expansion by free electrons proportionally to the deformation potential of the conduction-band minimum occupied by this charge, (iii) different thermal expansion of the undoped and doped samples. The experiments have been performed by using the high resolution X-ray diffraction at 77-770 K on AlGaAs:Te and GaAs:Si

Near IR Refractive Index for GaInN Heavily Doped with Silicon

The authors report on growth and results of infrared measurements of GaInN heavily doped with silicon. The lattice matched to GaN epitaxial layer of $Ga_{0.998}In_{0.002}N:Si$ has been grown in plasma assisted molecular beam epitaxy in the metal rich conditions. The room temperature Hall concentration and mobility of electrons are 2× $10^{20} cm^{-3}$ and 67 $cm^{2}$/(Vs), respectively. The refractive index has been determined by variable angle spectroscopic ellipsometry. The refractive index exhibited a significant reduction of its value (from 2.25 to 2 at 1.55 μm) at near IR range where are the main interests of potential applications for nitride based intersubband devices. Reported here values of refractive indices at 1.55 and 1.3 μm are appropriate for fabrication of cladding layers with the required contrast to GaN for intersubband devices. The observed drop of refractive index is attributed to the carrier-induced plasma edge effect, which has been directly observed in reflectance spectrum

III-V Semiconducting Nitrides Energy Gap under Pressure

In this paper we present overview of our recent experimental and theoretical results concerning electronic band structure of III-V nitrides under pressure. It is shown here that the pressure coefficients of the direct gap for studied nitrides are surprisingly small. To describe tendency in changes of the gap with pressure we use a simple empirical relation

On the applicability of InGaP:Si and AlGaAs:Sn piezoresistive pressure sensors in the 2.5 GPa range

Resistivity and Hall concentration was measured in several InGaP:Si and graded-gap AlGaAs:Sn epitaxial layers as a function of temperature from 77 to 350 K and of hydrostatic pressure up to 2.5 GPa. Strong pressure variation of resistivity was found together with weak temperature dependence in both types of samples which makes them good candidates for piezoresistive pressure sensors. The common origin of these properties seems to be the broad distribution of impurity states resonant with the conduction band. In InGaP:Si, the broadening of the impurity states is probably due to alloy splitting while in graded-gap AlGaAs:Sn the composition gradient leads to the smearing of impurity states with respect to the conduction-band edge. The optimum performance of the sensors can be expected if we combine the two mechanisms, i.e., in graded-gap InGaAlP:Si layers.This work was supported by the Committee for Scientific Research (KBN) through grant no. 8T 10C 027 11.Peer reviewe

Two-Electron DX State in CdTe:In

In this paper we investigate electron emission/capture from/to the DX state of indium in CdTe by means of high pressure freeze-out cycle and steady-state photo-conductivity experiments. The results indicate that the DX state is occupied by two electrons. A comparison with deep level transient spectroscopy data shows that two-electron emission occurs at low temperatures, while one-electron emission takes place at high temperatures

Control of Mg doping of GaN in RF-plasma molecular beam epitaxy

NRC publication: Ye

Weak Antilocalization in Quantum Wells

Spin relaxation in degenerated two-dimensional (2D) electron gas is studied by measurements of the magnetic field dependence of the weak antilocalization corrections to the conductivity in GaInAs quantum wells. Consistent quantitative (up to order of magnitude) description of weak antilocalization data on GaAs like heterojunctions and quantum wells was obtained. Our results show that spin precession around the effective magnetic field direction as described by the Dyakonov-Perel model is the main spin relaxation mechanism in degenerated 2D electron gas in semiconductors with no inversion symmetry