Surface passivation investigation on ultra-thin atomic layer deposited aluminum oxide layers for their potential application to form tunnel layer passivated contacts

Abstract

The surface passivation performance of atomic layer deposited ultra-thin aluminium oxide layers with different thickness in the tunnel layer regime, i.e., ranging from one atomic cycle (∼0.13 nm) to 11 atomic cycles (∼1.5 nm) on n-type silicon wafers is studied. The effect of thickness and thermal activation on passivation performance is investigated with corona-voltage metrology to measure the interface defect density Dit(E) and the total interface charge Qtot. Furthermore, the bonding configuration variation of the AlOx films under various post-deposition thermal activation conditions is analyzed by Fourier transform infrared spectroscopy. Additionally, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) is used as capping layer on ultra-thin AlOx tunneling layers to further reduce the surface recombination current density to values as low as 42 fA/cm2. This work is a useful reference for using ultra-thin ALD AlOx layers as tunnel layers in order to form hole selective passivated contacts for silicon solar cells.

Ultrathin Aluminum Oxide Films Induced by Rapid Thermal Annealing for Effective Silicon Surface Passivation

“…[30] The results indicate that the RTAinduced Al 2 O 3 films can achieve remarkable passivation effect, even better than the commonly used ALD method. Although the measured lifetimes in all samples are lower as compared with those by ALD Al 2 O 3 films, [31,32] solar-grade silicon wafers with lower τ bulk are used in this work. The thermal ALD equipments are commonly used in photovoltaic industry and the ALD-Al 2 O 3 films can be a good reference here.…”

Giant Conductivity Modulation of Aluminum Oxide Using Focused Ion Beam

“…Correspondence: hmohseni@northwestern.edu Aluminum oxide (Al 2 O 3 ) is one of the most widely employed dielectric materials, thanks to its excellent insulating properties 1 , mechanical hardness and resistance 2 , and biocompatibility 2,3 , with applications ranging from device passivation 1,[4][5][6][7][8] , MOSFET gate [9][10][11][12][13] , to biomedical implants and antifouling passivation 2,3,14,15 . Electrical functionalization of Al 2 O 3 via reliable and spatially-accurate control of its conductivity could enable novel sensing technologies encompassing electrical contacts embedded in a mechanically hard, chemically inert, and electrically insulating dielectric matrix.…”

Spatial Atomic Layer Deposition of Aluminum Oxide as a Passivating Hole Contact for Silicon Solar Cells

“…[21] These characteristics make Al 2 O 3 a promising candidate as a tunneling passivation layer for solar cell contacts in an MIS structure [22] or coupled with a separate carrier-selective material, such as doped polysilicon, [23] molybdenum oxide, [24,25] titanium oxide, [26] or even organic hole contact materials. [27] However, this insulating layer has to be thin enough to achieve a high probability of tunneling. Al 2 O 3 passivation layers can be deposited at manufacturing scale using spatial atomic layer deposition (ALD), [28] plasma-enhanced chemical vapor deposition (PECVD), [29] and atmospheric pressure CVD (APCVD).…”