We have carried out a search for circumstellar disks around Herbig Be stars using the NRAO Very Large Array (VLA) and the IRAM Plateau de Bure (PdB) interferometers. In this Paper, we present our new VLA and PdBI data on the three objects MWC 297, Z CMa and LKHa 215. We have constructed the SED from near-IR to centimeter wavelengths by adding our millimeter and centimeter data to the available data at other wavelengths, mainly Spitzer images. The whole SED has been fitted using a disk+envelope model. In addition, we have compiled all the disk millimeter observations in the literature and made some statistics. We show that the disk mass is usually only a small percentage (less than 10%) of the mass of the whole envelope in HBe stars. Concerning the disks, there are large source to source variations. Two disks of our sample, R Mon and Z CMa, have similar sizes and masses to those found in T Tauri and Herbig Ae stars. The disks around MWC 1080 and MWC 297 are, however, smaller (rout<100 AU). We have not detected at milimeter wavelengths the disks towards MWC 137 and LkHa 215 which implies an upper limit to the mass and the size of the possible circumstellar disks. The comparison between our data and previous results in T Tauri and Herbig Ae stars shows that although massive disks (0.1 Msun) are found in very young objects (10^4 yr), the masses of the disks around Herbig Be stars are usually 5-10 times lower than those around lower mass stars. We propose that disk photo-evaporation is the responsible for this behavior. In Herbig Be stars the UV radition disperses the gas of the outer disk on a time-scale of a few 10^5 yr. Once the outer part of the disk is gone, the entire gaseous disk is photo-evaporated in a very short time-scale (10^5 yr) and only a small dusty disk composed of large grains remains.