AlGaN-based LEDs for UV-C-light emission still suffer from relatively poor efficiency. Besides problems with carrier injection and light extraction, strong piezoelectric fields in the optically active region originating from lattice mismatch between quantum wells and barrier material are a major issue. Mixing only few percent of boron into the AlGaN active region may be sufficient to achieve lattice matched conditions, thus decreasing the influence of the quantum-confined Stark effect on the radiative recombination efficiency. However, the epitaxial growth of AlBGaN layers with sufficient crystalline quality is still a challenge, particularly due to the low solubility of boron in AlGaN and the low mobility of boron ad-atoms on the surface. Consequently, only extremely weak luminescence has been reported on layers containing few percents of boron. By thoroughly optimizing the metalorganic vapor phase epitaxial growth of AlBGaN layers with a boron content of some percent, we could achieve similar luminescence intensities as for reference AlGaN layers along with smooth hetero-interfaces and low surface roughness as measured by TEM and AFM. Besides studying the influence of basic growth parameters like temperature, V-III ratio etc., we investigate possible improvements by an optimized pulsed precursor supply sequence. To reduce the unintentional doping with impurities like oxygen or carbon, typically attributed to the standard boron precursor tri-ethyl boron (TEB), we investigate the novel metalorganic precursor tri-isopropyl-boron (TiPB). Its lower vapor pressure as compared to TEB facilitates a controlled incorporation of small B amounts. First PL spectra of AlBGaN layers grown with TiPB show promising data.