Growth and electrical characterisation of δ-doped boron layers on (111) diamond surfaces

Abstract

A plasma enhanced chemical vapor deposition protocol for the growth of d-doping of boron in diamond is presented, using the (111) diamond plane as a substrate for diamond growth. AC Hall effect measurements have been performed on oxygen terminated d-layers and desirable sheet carrier densities ($10 13 cm À2) for field-effect transistor application are reported with mobilities in excess of what would expected for equivalent but thicker heavily boron-doped diamond films. Temperature-dependent impedance spectroscopy and secondary ion mass spectroscopy measurements show that the grown layers have metallic-like electrical properties with high cutoff frequencies and low thermal impedance activation energies with estimated boron concentrations of approximately 10 20 cm À3. V

Hole transport in boron delta-doped diamond structures

“…9,10 The most recent of these works reported a low sheet density (p S ' 10 13 cm À2 ) and a hole mobility (l H ¼ 13 cm À2 =V Á s) larger than the one expected for highly doped diamond at room temperature in d-structures on [111]-oriented diamond substrates. 9 Unfortunately, no temperature dependence of p S and l H in d structures has been reported so far. It will be shown in this work that the analysis of the temperature dependence of p S ðTÞ and l H ðTÞ is essential in order to distinguish the contribution of each conduction path (buffer/high B-doped layer/cap layer) to the measured (mixed) conductivity.…”

“…6,7 Temperature dependent impedance spectroscopy measurements have been recently performed to identify the different conduction paths in the stacked structures. 8,9 Hall effect combined to four probes resistivity measurements have also been used to measure the sheet density (p S ) and the carrier mobility (l H ). 9,10 The most recent of these works reported a low sheet density (p S ' 10 13 cm À2 ) and a hole mobility (l H ¼ 13 cm À2 =V Á s) larger than the one expected for highly doped diamond at room temperature in d-structures on [111]-oriented diamond substrates.…”

“…8,9 Hall effect combined to four probes resistivity measurements have also been used to measure the sheet density (p S ) and the carrier mobility (l H ). 9,10 The most recent of these works reported a low sheet density (p S ' 10 13 cm À2 ) and a hole mobility (l H ¼ 13 cm À2 =V Á s) larger than the one expected for highly doped diamond at room temperature in d-structures on [111]-oriented diamond substrates. 9 Unfortunately, no temperature dependence of p S and l H in d structures has been reported so far.…”

Transport behavior of holes in boron delta-doped diamond structures

“…A practical target for the sheet density giving a combination of high current and gate control is 1-1.5×10 13 cm -2 . Applying these boundary conditions, one can determine that the required delta layer profile with B peak comparable to the metal-insulator transition has thickness <1 nm [17]. It is expected that a percentage of the holes confined in the ground state of the delta layer where the mobility is low due to ionized impurity scattering [16], are either thermally excited into higher energy subbands in the potential well, or ideally into bulk states with very little wavefunction overlap with the doped layer [18].…”

Polycrystalline Boron-doped Diamond Electrolyte-solution-gate Field-effect Transistor Applied to the Measurement of Water Percentage in Ethanol

“…Although Si-ISFETs with tantalum pentoxide (Ta2O5) and silicon nitride (Si3N4) show good response compared to the glass-type pH sensor, they still require over 30 s for obtaining a stable output. Recently, we have reported a no-gate-insulator electrolyte-solution-gate field-effect transistor (SGFET) with a single-crystal diamond surface-channel, [5][6][7][8] with a polycrystalline diamond surface-channel, and with a borondoped diamond surface-channel, [9][10][11] and have fabricated oxygenterminated and nitrogen-terminated diamond SGFETs with good pH sensitivity.…”