Signatures of the semiconductor crystallographic orientation on the charge transport across non-epitaxial diodes

Abstract

The hot electron attenuation length of Ag is measured utilizing ballistic electron emission microscopy on nanoscale Schottky diodes for Si(001) and Si(111) substrates. Marked differences in the attenuation length are observed at biases near the Schottky barrier depending upon the substrate orientation, increasing by an order of magnitude only for Si(001). These results provide clear evidence that the crystallographic orientation of the semiconductor substrate and parallel momentum conservation affect the charge transport across these interfaces. A theoretical model reproduces the effect that combines a free-electron description within the metal with an ab-initio description of the electronic structure of the semiconductor.

Nanoscale mapping of the W/Si(001) Schottky barrier

“…16 BEEM and BHEM have been used to measure the Schottky barrier height of many different metals to semiconductor interfaces. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] BEEM and BHEM are three terminal scanning tunneling microscopy (STM) techniques; hot electrons (BEEM) or holes (BHEM) are injected into a grounded metal film and travel ballistically towards the interface. Electrons (or holes) which have enough forward momentum after traveling through the metal to surmount the Schottky barrier pass into the semiconductor and are collected as the BEEM (or BHEM) current.…”

Schottky barrier height measurements of Cu/Si(001), Ag/Si(001), and Au/Si(001) interfaces utilizing ballistic electron emission microscopy and ballistic hole emission microscopy

“…The SBHs for many metal/semiconductor systems have been extensively studied using BEEM and BHEM. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] With BEEM the tip can be positioned with a Electronic address: vlabella@albany.edu nanoscale resolution giving spatially resolved spectra and barrier heights, which has been performed for Au/GaAs(001) diodes where a Gaussian distribution of barrier heights was observed in support of interface dipole models. 27 The power law form of the Bell and Kaiser model is the standard method for extracting the Schottky barrier height from the BEEM spectra.…”

Nanoscale Schottky barrier visualization utilizing computational modeling and ballistic electron emission microscopy

“…Using Matthiessen's rule (1/λ = 1/λ e + 1/λ i ) to calculate the attenuation length at 1 eV for all these samples puts them in the 10-20 nm range, which is similar to lengths measured using attenuation length studies with BEEM [98,71,99,100]. This calculation and the simulations are performed using a o and E F for silver.…”

“…The best fit was found with two barrier heights, where the addition of Coulomb scattering did [58,40,96]. The included region's barrier height is altered due to the continuity of the electrostatic potential at the interface [41,91,97,71]. The modeling predicts a Ag:Au barrier height ratio of 90:10 for the 30 nm thick silver and 18:82 for the 5 nm silver.…”

“…Unlike elastic scattering, inelastic scattering is an energy dependent process and the total probability of the electron scattering inelastically is inversely proportional to the total energy of the electron squared, 1/E 2 , and is captured by the inelastic mean free path 33) where E is the electron energy, A is a material specific scaling parameter of the metal layer, E F is the Fermi energy [71,11].…”