The present disclosure describes a storage device including a top panel, a bottom panel, a back panel, a front panel, and two side panels configured to form an enclosed volume. The storage device further includes multiple slots disposed at inner surfaces of the two side panels and configured to hold a substrate, a gas diffuser disposed at an inner surface of the back panel and configured to provide a purge gas to the enclosed volume, an isolation gas device disposed on an inner surface of the top panel and adjacent to a top portion of the front panel, and an isolation gas line configured to connect the isolation gas device to the gas diffuser. The isolation gas device is configured to inject the purge gas into a front portion of the storage device and in a direction from the top panel toward the bottom panel.