The application of molecular beam epitaxy (MBE) to the growth of compound semiconductors for devices and monolithic circuits requires excellent film uniformity and reproducibility of growth conditions. Conventional conical crucible cells for group III elements typically provide excellent film uniformity but exhibit a significant flux transient upon shutter opening due to the cooling of the melt surface. Flux transients result in poor control over initial growth stoichiometry and uncertainty over the initial film parameters which limit film reproducibility. This paper reports on a unique pyrolytic boron nitride (PBN) crucible arrangement for group III elements which simultaneously provides excellent film uniformity and a low flux transient. The cell utilizes a deep PBN crucible for a large recessed melt volume and a PBN insert to maintain beam uniformity. The cell provides film thickness and doping variations of less than 2% across a 2‐in.‐diam wafer and a flux transient of less than 3% when the shutter is opened. The usable melt volume is 20 cm3and the operating temperature is approximately 100 °C lower than that of the conical crucible cell. The large cell volume increases run time between cell recharging over conventional conical crucible cells. The melt location deep in the furnace provides long term temperature stability and reduces long term growth rate variations. The high material quality and low oval defect density (<500 cm−2) are comparable to conventional conical cells. The results of the measurement of film parameters are presented and the operation of the cell is described.