Performance of metamorphic transistors with δ-doped structures

The interesting dc, microwave, and power performance of double and single δ-doped metamorphic high electron mobility transistors (MHEMTs), grown by molecular beam epitaxy, are studied. Because of the use of a double δ-doped structure, the increase of carrier density and uniform distribution of carriers within the channel are found. Therefore, the superior characteristics in the drain saturation current of 544.4 (523.9) mA/mm, extrinsic transconductance of 361.2 (312.4) mS/mm, drain current operation region of 236.9 (227.4) mA/mm, unity current gain cutoff frequency of 55.1 GHz, maximum oscillation frequency of 129.17 GHz, output power of 15.35 dBm, power gain of 24.65 dB, and power added efficiency of 39.4% could be achieved for a 0.6 × 100 μm² gate dimension MHEMT at 300 (510) K. With increasing the temperature from 300 to 510 K, the slight temperature variation rates are also found for the studied device with a double δ-doped structure.On the other hand, the kink effect and impact ionization for the studied device with a double δ-doped structure are considerably suppressed.