We present a study of lateral silicon p-i-n light-emitting diodes, fabricated on SOI substrates. The p+ and n+ junctions were varied between conventional and ultra-shallow, utilizing pure-B and pure-P doping techniques. The impact of junction changes on both current-voltage behavior and light emission is discussed, based on experimental results and device modeling. The results stipulate that only a balanced carrier injection leads to efficient light emission and that uniform light emission across the intrinsic region can be obtained with a well-chosen p-i-n architecture.