An impedance spectroscopic investigation of the electrical properties of δ-doped diamond structures

Abstract

Impedance spectroscopy has been used to investigate the conductivity displayed by diamond doped with boron in an intrinsic-δ-layer-intrinsic multilayer system with differing δ-layer thicknesses. Carrier transport within 5 nm δ-layer structures is complex, being dominated by conduction in the interfacial regions between the δ-layer and the intrinsic regions, as well as conduction within the δ-layer itself. In the case of 3.2 nm thick δ-layers the situation appears improved with uncapped samples supporting only two conduction paths, one of which may be associated with transport outside of the δ-layer, the other low transport within the δ-layer complex diamond structures. Introduction of the capping layer creates a third conduction path associated with unwanted boron in the capping layer-δ-layer interface.

Атомный Состав И Электрофизические Характеристики Эпитаксиальных Слоев CVD Алмаза, Легированных Бором

“…Однако большие значения энергии активации примеси создают проблемы получения легированных слоев с необходимыми для полупроводниковых приборов свойствами. Поэтому мно-гими группами [2][3][4][5][6][7][8][9] ведутся исследовательские работы по изучению возможности получения эпитаксиальных пленок алмаза электронного и дырочного типов про-водимости при комнатной температуре. С этой целью применяется сильное легирование, которое позволя-ет существенно снизить энергию активации примеси.…”

Transport behavior of holes in boron delta-doped diamond structures

“…We note that conduction in parallel channels in delta layers was first invoked to explain impedance spectroscopy results [18].…”

“…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]. The expectation is that there will be a direct device benefit from an enhancement in mobility for nanometer thickness delta-layers.…”