A method includes forming a semiconductor fin, forming a dummy gate on a top surface and sidewalls of the semiconductor fin, and removing the dummy gate to form a recess. The material has a high emission efficiency and an good film-formability, and is suitably used for production of large-area device and mass-production thereof. The method may additionally include determining a healthy inventory level of the item that exceeds a target inventory level by a function of the sales demand rate and the breakeven holding time, and, if a current inventory level of the item exceeds the healthy level, declining to purchase units of said inventory item for the purchase price. The forecast caching server keeps a database of all the addresses of all stored pages in all caching servers that it controls, as well as historic data.