Primary pressure measurements down to 10−6 Pa

Frequency dependence of hot carrier a.c. conductivity of covalent semiconductors is studied considering scattering due to both acoustic and optical phonons. It is found that the effect of the optical phonons on the real part of the conductance is not significant, but the value of the imaginary part of the conductance is enhanced. The dependence of conversion efficiency for third harmonic generation on the frequency and amplitude of the fundamental signal is also discussed. The results agree qualitatively with those obtained from a consideration of acoustic phonons alone; the magnitude of the conversion efficiency, however, is found to be increased on including the effects of the optical phonons.

https://iopscience.iop.org/article/10.1088/0508-3443/16/10/306/pdf

Hot carrier a.c. conductivity and harmonic generation in semiconductors

In this paper the authors have investigated the generation of the third harmonic by microwaves, in a homogeneous semiconductor at low temperatures. The effect of ionized impurity scattering has been taken into account and it has been shown that, at low temperatures, the effect of the optical mode of scattering on the amplitude of the third harmonic is small. An approximate solution for the amplitude of the third harmonic part in the reflected and transmitted components of a large amplitude electromagnetic wave, incident normally on a slab of semiconducting material, is obtained, and numerical results have been presented for a few typical parameters It has been shown that a third harmonic of about 12% may be generated in the reflected wave when an incident electromagnetic wave of amplitude 1 e s u. cm-1 is allowed to fall on a typical germanium sample at 77 °K

Microwave third harmonic generation in semiconductors at low temperatures

A high‐power microwave propagating through a plasma‐filled waveguide gives rise to the generation of second and third harmonic waves because of ponderomotive force and energy‐dependent collisions, respectively. The generated harmonics possess a very different kind of intensity distribution than that of the normal modes. The efficiency of second harmonic generation is resonantly enhanced at some optimum size of the waveguide such that 2β1=β2, i.e., n2π2/b2+(m2−4) π2/a2= 3ωp2/c2 where β1 and β2 are the propagation constants of fundamental and second harmonic modes. This effect might account for the observed high yield of second harmonic generation in laser‐produced plasmas. The third harmonic power, however, shows a monotonic rise (tending towards a saturation value) with the width of the waveguide.

Microwave harmonic generation in a plasma-filled waveguide

Using Boltzmann's transfer equation for electrons, an expression is derived for the third harmonic component in the current density when a plane polarized microwave is normally incident on a free-space-semiconductor interface; the ionized impurity scattering is considered as the sole mechanism of electron scattering. The non-parabolicity of the energy bands of InSb is taken into account by using Kane's model. A numerical estimate of the amplitude of the third harmonic wave in the reflected component is made for typical values of various parameters.

Sadato Yabuki

Papers

Microwave Harmonic Generation with Hot Electrons in n-Germanium