Comparison between aluminum oxide surface passivation films deposited with thermal ALD, plasma ALD and PECVD

Abstract

Surface passivation schemes based on Al2O3 have enabled increased efficiencies for silicon solar cells. The key distinguishing factor of Al2O3 is the high fixed negative charge density (Qf = 10 12 -10 13 cm -2 ), which is especially beneficial for p-and p+ type c-Si, as it leads to a high level of field-effect passivation. Here we discuss the properties of Al2O3 surface passivation films synthesized with plasma atomic layer deposition (ALD), thermal ALD (using H2O as oxidant) and PECVD. We will show that with all three methods a high level of surface passivation can be obtained for Al2O3 deposited at substrate temperatures in the range of 150-250 o C. Furthermore, the role of chemical and field-effect passivation will be briefly addressed. It is concluded that the passivation performance of Al2O3 is relatively insensitive to variations in structural properties. Al2O3 is therefore a very robust solution for silicon surface passivation.

Investigation of sidewall damage induced by reactive ion etching on AlGaInP MESA for micro-LED application

“…In our case, the passivation involves the removal of the native oxide layer and the formation of a thin protective layer to prevent further atmospheric oxidation by using for example sulfur treatment with ammonium sulfide (NH4)Sx [34], [35]. Other techniques could be used such as plasma treatment [36], nitridation [37] or passivation with film deposition [38] such as ALD Al2O3 deposition [9], [29]. Finally, these results demonstrate the possibility to conduct studies about etching impact or passivation treatment only at the MESA step which is cost effective and easier compared to I-V-L measurement that require fully processed wafers.…”

Structural Properties of Al–O Monolayers in SiO2 on Silicon and the Maximization of Their Negative Fixed Charge Density

“…This contrasts with the deposition of thick Al 2 O 3 films directly onto Si wafers. 61 Because the crucial interface SiO 2 on the Si wafer is fabricated separately (here by RTO or PECVD), the oxidation potential of the ALD method (H 2 O vapor or O radicals) is irrelevant and decoupled from the ALD-Al 2 O 3 process.…”

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.…”