We report on the influence of doping, temperature, porosity, band gap, and oxidation on the photoluminescence (PL) properties of anodically etched porousa-Si:H anda-Si:C:H thin films. Only boron-doped,p-typea-Si:H samples exhibited visible photoluminescence. Two broad PL peaks at∼1.6and∼2.2 eVare apparent in room temperature PL spectra. The intensity of the 2.2 eV peak as well as the nanovoid density in the unetcheda-Si:H layers both correlate well with boron concentration. We see evidence of discrete defect or impurity levels in temperature-dependent luminescence measurements, where we observe multiple luminescence peaks. Unlike in porous crystalline silicon, the luminescence energy in porous amorphous silicon does not change with porosity. We do, though, observe a correlation of luminescence energy with band gap of the startinga-Si:C:H films. Oxidation, either native or anodic, reduces photoluminescence intensity. We discuss the implications of these observations on the nature of the luminescence mechanism. ©1997 American Institute of Physics.