Keldysh_beamTempWidth\ THz-STM

THz-STM

A technique pioneered by Prof. Frank Hegmann at University of Alberta.

Related Topics

THz related Calculations

Laser repetition rate[Hz]
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THz beam power [W]
Energy per pulse [J]
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Average THz current [pA] with THz modulation OFF (divide by 2 if modulation was ON)
Electrons per pulse with THz modulation OFF (multiply by 2 if modulation was ON)

Scan Speed Calculator for THz scanning

Conuctance Lock-In calculation

Lock-in Voltage Output Calibration

\begin{equation} I_{THz,avg}=(e f_{rep})\times N_e^{-}=g\ s\ K_{5077}\frac{V_{out}}{10 V} \end{equation} \begin{equation} N_e^{-}=K_{5077}\times s \times 2596 [e^- /V^2] \times V_{out} \end{equation}

Electro-Optic Sampling

The THz pulse electric field is given by \begin{equation} E_{THz}(\tau)=\frac{\lambda}{2 \pi n_O^3 r_{41} L} \Delta \Phi(\tau) \end{equation} The differential phase retardation is given by \begin{equation} \Delta \phi=\sin ^{-1} \left(\frac{I_y-I_x}{I_y+I_x}\right) \approx \frac{I_y-I_x}{I_y+I_x}\end{equation}

I-V-E Plots

Load Data for I-V curve:
Load Data for EOS waveform:
Set Bias Voltage:
Setpoint=
THz pulse scaling factor:

E-field at peak = V/cm
E-field at peak =

Field Penetration through a thin sample

$v=$ m/s

$\alpha=$ $m^{-1}$

$\delta_p=$ $nm$

$\delta_e=$ $nm$

$R_\perp=$

$T_\perp=$

$\epsilon_1=$

$\epsilon_2=$

$\theta_t=$

$R_s=$

$R_p=$

$T_s=$

$T_p=$

Mobility= $cm^2/Vs$

Drift Velocity= cm/s

Distance traveled/Hemisphere radius= nm

Hemisphere Volume= $m^3$

Electrons inside hemisphere=

Max. Avg. current= pA

where {Volume}_{Hemisphere}=$\frac{2}{3}\pi r^3$ , (mobility) $\mu=V_{atomic}*\sigma / e$, (drift velocity) $v=\mu E$ , $I_{avg}= (Num)e^- \times 1.602E^{-19} C \times LaserRepRate $

Laser peak values and Keldysh parameter

The Keldysh parameter is given by \begin{equation} \gamma=\sqrt{\frac{\Phi}{2K}}=\frac{\omega}{e F}\sqrt{2 m_e \Phi} \end{equation} where $\Phi$ is the work function of the material, $K=\frac{e^2 F^2}{4 m_e \omega^2}$ is the ponderomotive force, $\omega$ is the laser frequency, $m_e$ is the electron mass and $F$ is the laser peak electric field.