Article

D - centers in intracenter Si:P lasers

Leibniz Institute for Crystal Growth, Berlín, Berlin, Germany
Journal of Applied Physics (Impact Factor: 2.19). 07/2005; 97(11):113708 - 113708-6. DOI: 10.1063/1.1922091
Source: IEEE Xplore

ABSTRACT The terahertz Si:P laser is based on the 2p0→1s(T2) transition of neutral phosphorus donors D0 that are photoionized by radiation from a C O 2 laser. The manifestation of negatively charged D- donor centers has been studied. The population of D- centers as well as D0 donor states are calculated and the amplification provided by D0 centers is compared with the absorption by D- centers. The small signal gain and laser threshold have been measured for a set of Si:P lasers with different degrees of compensation (doping by neutron transmutation). It is shown that absorption by D- centers terminates the laser action in Si:P lasers with small compensation (K≪1%) for pump intensities less than 1 kW cm -2 . At higher excitation levels (≫10 kW cm -2) , or for larger compensation, absorption by D- centers becomes negligible.

0 Followers
 · 
97 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: We studied the hybrid system composed of a polarizable nanoparticle and a quantum well. For coupled oscillations of dipole excitations of the nanoparticle and two-dimensional electron gas, we determined frequencies and damping of the Landau-type. We found that under the drift of two-dimensional electrons, electrostatic coupling between the nanoparticle and the quantum well gives rise to a novel type of electrical instability in the terahertz frequency range. Under this electrical instability, amplitudes of the dipole and plasma oscillations increase in time due to the energy transfer from the drifting electrons. The instability arises when the electron drift velocity exceeds a critical value. Long relaxation times of the dipole excitations of the nanoparticle are favorable for development of the instability. We presented estimates, which demonstrate that the instability can be realized in quantum dot—quantum well hybrid systems fabricated by contemporary semiconductor technologies. This instability can provide a new mechanism for generation of THz radiation.
    Journal of Applied Physics 06/2011; 109(11):114318-114318-6. DOI:10.1063/1.3594682 · 2.19 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The first silicon laser has been reported in the year 2000. It is based on impurity transitions of the hydrogen-like phosphorus donor in monocrystalline silicon. Several lasers based on other group-V donors in silicon have been demonstrated since then. These lasers operate at low lattice temperatures under optical pumping by a mid-infrared laser and emit light at discrete wavelengths in the range from 50 µm to 230 µm (between 1.2 THz and 6.9 THz). Dipole-allowed optical transitions between particular excited states of group-V substitutional donors are utilized for donor-type terahertz (THz) silicon lasers. Population inversion is achieved due to specific electron-phonon interactions inside the impurity atom. This results in long-living and short-living excited states of the donor centers. Another type of the THz laser utilizes stimulated resonant Raman-type scattering of photons by a Raman-active intracenter electronic transition. By varying the pump laser frequency, the frequency of the Raman intracenter silicon laser can be continuously changed between at least 4.5 THz and 6.4 THz. The gain of the donor and Raman-type THz silicon lasers is in the order of 0.5 cm-1 to 10 cm-1 which is similar to the net gain realized in THz quantum cascade lasers and infrared Raman silicon lasers. In addition, fundamental aspects of the laser process provide new information about the peculiarities of electronic capture by shallow impurity centers in silicon, lifetimes of nonequilibrium carriers in excited impurity states, and electron-phonon interaction.
    physica status solidi (b) 01/2013; 250(1):9-36. DOI:10.1002/pssb.201248322 · 1.61 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Small signal gain measurements of optically excited terahertz silicon lasers are reported. Two types of lasers, Si:P and Si:Bi, were investigated. They were optically excited with radiation from a free electron laser or a CO2 laser. The experiments were performed with an oscillator-amplifier scheme where one sample serves as a laser while the other one is an amplifier. In case of the free electron laser the pump frequency corresponds to intracenter excitation of the 2p0 or 2p± states of the P and Bi Coulomb centers, and the gain was determined for the 2p0→1s(E), 2p0→1s(T2) transitions in Si:P and the 2p±→1s(E) transition in Si:Bi. Pumping with a CO2 laser leads to photoexcitation of the Coulomb centers. In this case the gain was determined for the 2p0→1s(T2) of Si:P transition. The gain for intracenter pumping is in the range 5−10 cm−1 while for photoexcitation the gain is considerably less, namely ∼ 0.5 cm−1. The experimental results are analyzed and found to be in good agreement with theoretical calculations based on balance equations.
    Journal of Applied Physics 11/2007; 102(9):093104-093104-5. DOI:10.1063/1.2804756 · 2.19 Impact Factor