Electrons In InP Research Articles

Tunable 100 Gbaud Transmitter Based on Hybrid Polymer-to-Polymer Integration for Flexible Optical Interconnects

We introduce a hybrid integration platform based on the combination of passive and electro-optic polymers. We analyze the optical and physical compatibility of these materials and describe the advantages that our hybrid platform is expected to have for the development of transmitters in terms of operation flexibility and speed. We combine our platform with InP electronics and develop a transmitter with 22-nm tunability in the C-band and potential for serial non-return-to-zero on-off-keying operation directly at 100 Gb/s. We investigate its transmission performance at 80 and 100 Gb/s using dispersion uncompensated standard single-mode fiber and demonstrate bit-error rate (BER) lower than 10−10 at 80 Gb/s after 1625 m, lower than 10−10 at 100 Gb/s after 500 m, lower than 10−9 at 100 Gb/s after 1000 m, and BER 10−7 at the same rate after 1625 m. We also employ the transmitter inside an experimental setup, which aims to emulate an optical circuit switched (OCS) domain of an intradata center network, and demonstrate at 100 Gb/s the way, in which its wavelength tunability can resolve contentions and improve the flexibility and the efficiency of the network. Finally, we outline our next plans, including the development of flexible and ultra-fast transmitters for coherent systems using the same polymer-to-polymer integration platform.

Magnetospectroscopy of high-purity InP grown by gas source molecular beam epitaxy

Magneto-photoconductivity spectra related to the bound phonons and resonant polaron effect on Si donors in high-purity InP have been investigated. Not only the transition from the 1s ground state to bound phonon state (1s+LO) of Si donors, but also the antilevel crossings of the (3, 1, 0) metastable state with the bound phonon states (1s+LO) and (2p−1+LO) are clearly observed in high magnetic fields. The results demonstrate the bound phonon in Si-doped InP consists of both electron and phonon via multiphonon processes and there is a resonant interaction between LO phonons and impurity-bound electrons in InP.

Bistable magnetic resonance of conduction electrons in InP

The magnetic resonance of conduction electrons in InP exhibits a pronounced hysteresis with distorted line shapes. These features are quantitatively accounted for by considering the intrinsically bistable character of the dynamic nuclear polarization due to the Overhauser effect. The gross features of the resonance, its hysteresis, and the line shapes are controlled by the steady-state bistable nuclear field. It is shown that the effect of the long nuclear-relaxation time is compensated by the effects of the nuclear-field fluctuations. The respective contributions of the intrinsic bistability, the nuclear-relaxation rate, and the fluctuations are clearly identified by considering the bistable resonance as the overdamped motion of the spin system in a bistable potential.

A positron lifetime investigation of InP electron irradiated at 100 K

Positron lifetime investigations have been made on variously doped InP samples irradiated at 100 K with 2.5 MeV electrons. Three irradiation-produced positron lifetimes were found: 240±10, 265±10, and 330±20 ps which are, respectively, ascribed to VP, VIn, and VP⋅VIn vacancies in close association with interstitials. Total introduction rates of these defects were in the range of 0.6–1.2 cm−1. Observation of the defects depends on the position of the Fermi level. In n-type materials no evidence could be found for VP⋅PI, while in p-type material VIn⋅InI was not observed. Annealing studies up to 300 K show that VP⋅PI anneals slightly below 300 K, while VIn⋅InI anneals in part around 125 K, but a sizable fraction remains at 300 K. Divacancies begin annealing at 125 K, but some can persist to 300 K.

A 100 MW electron source with extremely high beam area compression

The development at INP electron optical system for a 7 GHz magnicon incorporating the high voltage diode gun based on a 120 mm oxide cathode with microperveance of 0.83 and high electrostatic compression of a beam as well as the guiding magnetic system are described here. The main problems and the concepts used for the formation of the super dense relativistic beam in the diode gun and its matching with magnetic system are described in detail. The geometry of the whole electron optical system is given and the results of numerical calculations for the beam dynamics are described. The experimental results of the formation of electron beam and its transportation through the guiding magnetic system are described. As a result of these experiments a beam of 100 MW ( U = 436 kV, I = 236 A) in a pulse of 2 μs is obtained. The measured diameter of a beam in magnetic system is about 2.5 mm and it is close to that of the Brillouin's. Thus, the total measured compression of a beam over area exceeds 2000, power density in a beam achieves 2000 MW/cm 2 and an energy density in a beam exceeds 4 kJ/cm 2.

Two-temperature technique for plasma-enhanced chemical vapour deposition growth of silicon-nitride on InP

The high mobility and saturated drift velocity of electrons in InP make the insulator/InP structure very attractive for high speed circuit applications. Despite this potential, however, a number of troubling problems, such as high density of interface states, formation of poor dielectrics, electrical instability and lack of reproducibility, remain to be solved. The established deposition methods can not satisfy simultaneously the requirements for low density of interface states and good dielectric properties of insulator [1]. The newly proposed twotemperature deposition technique offers a possible way of solving this problem [2]. In this method, a thin interracial layer is formed at a low temperature, then the bulk insulator is deposited at a higher temperature. The value of this technique has been proven for the SiO2/Si system. To the best of our knowledge, however, the application of this technique to insulator/III-V semiconductor has not been reported. In this letter, we report on the results of the two-temperature technique applied to form an SIN,/ InP structure, where SiN, was produced by the plasma-enhanced chemical vapour deposition (PECVD) method. The electrical properties were characterized by multifrequency capacitancevoltage ( C V ) measurements, 1 MHz conductance-voltage ( G V ) measurements and quasi-static C V measurements. The optimum deposition temperature was found to be about 200 °C for the first thin SiN, deposition. The substrates employed in this study were undoped n-type (n--~ 5.0 x 1015 cm -3) (100) InP wafers (Nippon Mining Co.). The wafers were first cleaned in a standard organic solution (trichloroethylene, acetone and methanol). To remove any native oxide on the surface, they were then etched with acid solution (H2SO4:H202:H20 = 3:1:1) for 60 s. After rinsing in deionized water, they were dried by N2 gas blow. After blowing, the SiN, deposition process was initiated immediately in the PECVD chamber. The PECVD apparatus used was designed inhouse and the reactor was a capacitivelycoupled hot wall type [3]. Silicon nitride films were deposited from the gas mixture of dilute silane (5% Sill 4 in N2), ammonia (99.999%) and nitrogen

Zeeman electron mass anomaly in InP as determined from orbital and spin splitting of donor 2P levels using high-resolution photoluminescence spectroscopy

The effective mass of an electron in InP determined from Zeeman splittings of the donor 2P level shows a strong magnetic field dependence. This Zeeman effective mass is approximately 45% smaller than the cyclotron mass at low magnetic fields. This was deduced from both the orbital and spin splittings of the 2P donor levels. The magnetic field splittings were determined from radiative transitions resulting from collapse of donor bound excitons leaving the terminal state in an excited state. The magnitude of the effect is much larger than that previously observed in GaAs. This anomaly is qualitatively explained on the basis of level mixing resulting from random static electric fields present throughout the crystal due to ionized impurity centers. The mass obtained from the orbital splitting is in good agreement with that obtained from the spin splitting.

MOVPE growth and characterization of strained layers

Strained layers of GaP/GaAsP/GaP grown on both (100) and (111) surfaces and InP/GaAs/InP have been grown by MOVPE. These layers have been investigated by photoluminescence and cathodoluminescence at low temperatures. Photoluminescence measurements show emission from all the structures. In the GaP/GaAsP/GaP structures the emission peaks are attributed to excitons recombining at donor sites, free excitons, and recombination of charge carriers localized by alloy fluctuations. In the InP/GaAs/InP structures emission attributed to electrons in InP recombining with holes in the strained GaAs layer is seen together with emissions which are probably related to interface defects. Using cathodoluminescence the formation of dislocations in the GaP/GaAsP/GaP system has been investigated. A significant difference is seen for growth on (100) and (111) surfaces. It is concluded that in both cases 60° dislocations are responsible for relieving the strain. It is demonstrated that a concentration difference of 2% As increases the dislocation density from 0 to 100 dislocations/mm in the GaP/GaAsP/GaP system grown on the (100) surface. From similar cathodoluminescence studies of the InP/GaAs/InP structures a critical thickness of above 30Åis deduced.

Growth and characterization of InP epilayers on ZnSehen;coated Si substrates by low-pressure metalorganic vapor phase epitaxy

Heteroepitaxial growth of InP on ZnSe-coated Si substrates by low-pressure metalorganic vapor phase epitaxy is reported for the first time. Single-crystal InP epilayers with specular surfaces can be obtained. The ZnSe buffer layer, which is evaporated onto the Si substrate in another furnace, is effective in reducing the magnitude of strain in the InP layer. The best room-temperature electron mobility of the undoped InP epilayer can reach 3100 cm2 /(V s) with a carrier concentration of 1.5×1015 cm−3 . It was found that the InP electron mobility is critically dependent on the ZnSe buffer-layer thickness. The efficient photoluminescence compared with that of InP homoepitaxy indicates that the InP heteroepilayer is of high optical quality.

Growth and characterization of InP/GaAs epilayers on Si substrates by low-pressure metalorganic vapor phase epitaxy

Heteroepitaxial growth of InP on Si with an intermediate GaAs buffer layer by low-pressure metalorganic vapor phase epitaxy is reported. Single-crystal InP epilayers with specular surfaces can be reproducibly obtained. The uniform composition of this heterostructure was identified by the Auger depth profile. The best room-temperature electron mobility of the undoped InP epilayer can reach 3250 cm2/V·s with a carrier concentration of 1×1015 cm−3. It was found that the InP electron mobility is critically dependent on the growth temperature. The 77 K photoluminescence (PL) of the InP layer exhibits a strong near-band-edge emission. No evident shift in PL peak energy for the InP/GaAs/Si sample compared with that for the InP homoepitaxial sample was first observed in this study. An evident effect of the GaAs buffer-layer thickness on the InP optical quality is also demonstrated.

Transient electronic transport in InP under the condition of high-energy electron injection

Transient transport of electrons in InP is studied under the condition of high-energy electron injection. This study makes use of a Monte Carlo simulation with the unique inclusion of realistic band-structure as derived from an empirical pseudopotential method. The results obtained herein for InP are qualitatively similar to those previously obtained by the authors for GaAs. Quantitatively, it is found that ultra-high electron drift velocities (≈10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> cm/s) persist for much higher electric fields and over much longer distance of electron traversal in InP as compared to GaAs.

Optical properties of copper-related centres in InP

A new Cu-related photoluminescence band in InP is reported. It consists of a sharp zero-phonon line at 1.2889 eV with sharp LO and 'gap mode' local phonon replicas to lower energy superimposed on a broad vibronic background. Zeeman studies show that the recombination process arises from an exciton bound to a neutral isoelectronic centre. Electron and hole g-values of 1.27 and 2.12 respectively are deduced, with both electron and hole having spin 1/2. The very strong diamagnetic shift of the spectrum is found to be equal to that of a shallow donor electron in InP. This demonstrates clearly that the hole is tightly bound in the short-range potential of the centre with binding energy EB h=127.5 meV and that the electron is then weakly bound in the Coulomb field of the hole (EB e=7.3 meV), so that the overall behaviour is of an isoelectronic donor. The thermal activation energy of the vibronic sideband of the luminescence is found to be 135+or-10 meV, in good agreement with the spectroscopic value of the hole binding energy.

Resonant inelastic light scattering by free electrons in InP

The single particle and collective excitations of free electrons in doped n-InP have been studied by resonant inelastic light scattering near the E 0 + Δ 0 optical energy gap. The resonant enhancements and spectral lineshapes are similar to those previously reported in n-GaAs. The resonant spectra by longitudinal coupled plasmon-phonons reveal the contributions of processes for which wavevector conservation breaks down.

Traps at the deposited insulator-InP interface— a discussion of a possible cause

Trapping of interface electrons in InP metal/insulator/semiconductor field effect transistors (MISFETs) has previously been reported. The rate of trapping appears to be strongly dependent on the fabrication process although the cause of the trap states is not presently known. In this paper a model for the cause of the traps is proposed based upon a review of the InP MIS literature and knowledge of the chemical composition of the InP native oxide. The model associates the traps with the presence of In 2O 3 near the insulator-InP interface. The In 2O 3 is formed either by oxidation of the InP surface or by a reaction between the InPO 4 native oxide and the depositing insulator. A number of assumptions have been made in order to fit the In 2O 3 trap model to the reported MISFET measurements. Thus, at this point the model should not be considered complete but a basis for further experiments.

Diffusion and the power spectral density of velocity fluctuations for electrons in InP by Monte Carlo methods

The low-frequency parallel and transverse diffusion coefficients for electrons in InP are calculated using Monte Carlo methods for lattice temperatures of 200, 300, and 500 K. The sensitivity of the computed values to the duration of the flight sampling time is investigated, and this is shown to be a consequence of the frequency dependence of the diffusion coefficient. To test this hypothesis the variation of the parallel diffusion coefficient with both frequency and field at 300 K is determined. For fields above threshold the parallel diffusion coefficient first rises from its low-frequency value to a maximum and thereafter decreases with increasing frequency; for fields substantially below threshold a slow monotonic decrease is observed.

Electron mobility in InP

Theoretical values of weak-field Hall mobility and Hall ratio of electrons in InP at 77K and 300K are presented for different impurity concentrations and compensation ratios. Calculations were done by an iterative method taking into account all the complexities of the band structure and the electron scattering mechanisms and using the most recent values of the physical constants. Calculated values are in close agreement with the recent experimental results.

Temperature dependence of the velocity/field characteristic of electrons in InP

Previous calculations of the velocity/field characterisitcs of electrons in indium phosphide at room temperature have been extended to cover the temperature range 200–500 K. Preliminary results for the diffusion coefficients are presented.

Measurement of effective mass of electrons in InP by infra-red Faraday effect

Measurement of effective mass of electrons in InP by infra-red Faraday effect

The magnetoresistance of electrons in InP and GaAs

The magnetoresistance of electrons in InP and GaAs

Carrier Mobilities in InP, GaAs, and AlSb†

ABSTRACT The majority carrier mobilities in n-type In P and GaAs and p-type AlSb havo been measured as functions of impurity concentration and temperature in single crystals. Considerations of scattering of the charge carriers by ionized donors and acceptors suggest lattice mobilities at 300°K of 11 500 cm2/volt sec for electrons in GaAs, 6600 cm2/volt sec for electrons in InP, and 450 cm2/volt sec for holes in AlSb. Total ionized impurity contents can be estimated from the effects of impurity scattering on the carrier mobilities. The temperature dependencies of the electron mobility due to lattice scattering in the InP and the hole mobilities in GaAs and AlSb are greater than T -2. Tho effective mass of tho holes in AlSb is about 0·4 m0.