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Porous silicon (Si) was fabricated by using three different wet etching methods, namely, direct current photo-assisted electrochemical (DCPEC), alternating CPEC (ACPEC) and two-step ACPEC etching. This study aims to investigate the structural properties of porous structures formed by using these etching methods and to identify which etching method works best.

Si n(100) was used to fabricate porous Si using three different etching methods (DCPEC, ACPEC and two-step ACPEC). All the samples were etched with the same current density and etching duration. The samples were etched by using hydrofluoric acid-based electrolytes under the illumination of an incandescent lamp.

Field emission scanning electron microscopy (FESEM) images showed that porous Si etched using the two-step ACPEC method has a higher porosity and density than porous Si etched using DCPEC and ACPEC. The atomic force microscopy results supported the FESEM results showing that porous Si etched using the two-step ACPEC method has the highest surface roughness relative to the samples produced using the other two methods. High resolution X-ray diffraction revealed that porous Si produced through two-step ACPEC has the highest peak intensity out of the three porous Si samples suggesting an improvement in pore uniformity with a better crystalline quality.

Two-step ACPEC method is a fairly new etching method and many of its fundamental properties are yet to be established. This work presents a comparison of the effect of these three different etching methods on the structural properties of Si. The results obtained indicated that the two-step ACPEC method produced an etched sample with a higher porosity, pore density, surface roughness, improvement in uniformity of pores and better crystalline quality than the other etching methods.

This study aims to propose a new model of Islamic cooperative mortgage of housing finance (ICOM) to provide a lower monthly initial amount with a longer tenure for the low- and middle-income members. This model is developed to ease the burden on borrowers concerning the high initial down payment (ID).

The ICOM model is a no-interest mortgage and is developed based on the cooperative home mortgage model by Ebrahim (2009). The model is verified using numerical examples to ensure its feasibility to produce lower monthly initial amounts and compared to the cooperative home mortgage.

From the numerical example, the ICOM model shows a lower monthly initial amount with a longer tenure compared to the cooperative home mortgage. The monthly payment is also lower than the cooperative home mortgage.

The authors compare their model with Ebrahim’s (2009) cooperative home mortgage because of a constraint of limited previous studies on housing finance. Therefore, this model is developed by considering the unaffordability of the initial down payment among low-income borrowers. As this model introduces a lower monthly initial amount, the authors expect it can reduce the unaffordability problem of high initial down payment.

The authors also expect that a lower monthly initial amount with a longer tenure can ease the burden among the low-income borrowers by reducing their consumption on housing.

This paper provides a non-interest Islamic cooperative mortgage and lower monthly initial amount with a longer tenure for the low- and middle-income borrowers.