AlGaAs/InGaAs heterostructure doped-channel FET's exhibiting goodelectrical performance at high temperatures

High-power and high-efficiency GaAs heterostructure field-effect transistors (FETs) are attracting tremendous attention in RF power amplifier applications. However, thermal effects can be an important issue in RF power devices, owing to the huge amount of heat generated during their operation. In this paper, the temperature-dependent characteristics of Al_0.3Ga_0.7As/In_0.15Ga_0.85 As doped-channel FETs (DCFETs) are investigated and compared with conventional pseudomorphic-HEMTs (pHEMTs) devices, in terms of their dc, microwave and RF power performance at temperatures ranging from room temperature to 150°C. Due to conducting carriers being less influenced by temperature and the better Schottky diode characteristics that can be obtained in DCFETs, the intrinsic device parameters and output performance remain almost constant at high temperatures, which also results in better device reliability. The performance variation of DCFETs associated with temperatures from 25°C to 150°C all fall within a single digit, i.e., output power (P_out, 16.2 dBm versus 15.8 dBm), power gain (G_p, 16.6 dB versus 15.1 dB), power added efficiency (PAE, 34.2% versus 31.3%), which is not the case for conventional pHEMTs. Therefore, DC devices are very promising for microwave power device applications operating at high temperature