We have developed a simple method to passivate industrially produced boron-doped emitters for n-type base silicon solar cells using an ultrathin (∼1.5nm) silicon dioxide layer between the silicon emitter and the silicon nitride antireflection coating film. This ultrathin oxide is grown at room temperature by soaking the silicon wafers in a solution of nitric acid prior to the deposition of the silicon nitride antireflection coating film. The n-type solar cells processed in such a way demonstrate a conversion efficiency enhancement of more than 2% absolute over the solar cells passivated without the silicon dioxide layer.

The effects of phosphorous gettering and hydrogenation on the minority carrier recombination at crystal defects in directionally solidified multicrystalline silicon are described. Representative industrial wafers, both p- and n-type, and current technologies for the gettering and hydrogenation are used. The main result of this work is a strong link between activation of extended crystal defects (ECDs) by gettering and their passivation by hydrogenation. It is shown that gettering or annealing increases the recombination at active as well as inactive ECDs. Surprisingly, hydrogenation can neutralize this change in activity due to the gettering. However, it neutralizes only part, at most, of the ECD activity already present before the gettering. Therefore, under current industrial processing techniques, these two high-temperature process steps individually give large change but together much less net change of the crystal defect activity. Related phenomena are observed in wafers with strongly varying impurity concentration. Finally, there is little difference in these observations between n- and p-type wafers.

Scanning tunneling microscopy has revealed the reorientation of one of the macrocyclic rings of the double-decker porphyrin complex [Ce(TPP-Fc)(C(22)OPP)] [TPP-Fc = 5-(4-(4-ferrocenylphenylethynyl)phenyl)-10,15,20-triphenylporphyrin; C(22)OPP = 5,10,15,20-tetrakis(4-docosyloxyphenyl)porphyrin] by 90 degrees between scans when the other ring is fixed on a surface. This libration was evidenced by monitoring the location of the appended ferrocene unit, which functioned as a molecular beacon signaling its position.

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Heteroepitaxial growth of indium gallium phosphide (In1-x Ga x P) with x ∼0.7 was successfully achieved on a silicon (Si) substrate by introducing step-graded buffer layers which consist of a gallium phosphide (GaP) buffer layer and In1-x Ga x P layers whose gallium (Ga) composition x decreases in steps toward the direction of the growth. For the GaP buffer layer, the effects of thermal cycle annealing (TCA) were studied using a Rutherford back scattering channeling (RBS-C) measurement. The layer was shown to be improved greatly and a high-quality heteroepitaxial GaP layer could be obtained in the region close to the surface by introducing TCA. For the In1-x Ga x P step-graded layers, the lattice strain, investigated using X-ray diffraction, was shown to be more relaxed using a Si substrate than using a GaP substrate. The growth of InGaP on a Si substrate with the step-graded layers is an effective method to reduce the strain in the InGaP layer.

The electrochemical capacitance-voltage (ECV) technique can practically profile carrier concentrations on textured surfaces, but reliable calibration of the surface area is strongly demanded since it plays a decisive role in calculating both the carrier concentration and the profiling depth. In this work, we calibrate the area factor of pyramidally textured surfaces by comparing ECV profiles with cross-sectional scanning electron microscopy image, and found out it is 1.66, and not 1.73 which was formerly assumed. Furthermore, the calibrated area factor was applied to POCl 3 and BBr 3 diffusions which resulted in comparable diffusion profiles for both textured and polished surfaces.