應用於無線通訊上的平面摻雜假晶功率高電子遷移率電晶體之研究

Abstract

本論文製作一種具有平面摻雜假晶功率高電子遷移率電晶體 (Power HEMT) ，文中並敘述各個製程步驟與技術，並藉著精確的製程控 制達成優良的元件特性以及高產率。 此元件的直流特性如下，1 mm×15mm 的元件具有 3.8 A 的飽和電流 (saturation current) 與超過 14 V的閘極-汲極崩潰電壓 (gate-to-drain breakdown voltage)，最大 互導率 (transconductance) 超過 260 mS/mm ，夾止電壓 (pinch-off) 為 -2.3 V，而飽合電壓 (saturation voltage;knee voltage) 為 2.3 V ，其有效飽和電壓 (effective knee voltage) 低至 0.3 V。 本 論文亦論及元件在 1.9 GHz以及在 3.0 V與 4.7 V汲極偏壓操作時的微波 功率特性。在 3.0 V 操作下，1mm×15mm 尺寸的元件具有 1.5 W 的最大 輸出功率 (maximum output power)，此時功率效益 (power-added efficiency) 為 40.8%，其線性增益 (linear gain) 為 12.62 dB。一分 貝衰減功率 (1-dB compression power) 為 29.13 dBm，此時功率效益為 46.8%. 在 4.7 V 操作下，此元件最大輸出功率為 2.87 W，此時 功率效益為 52.3 %，增益為 10.1 dB，線性增益為 13.65 dB。一分貝縮 減功率為 33.2 dBm ，其功率效率為 49.0 %。 在 4.7 V下，也 量測元件數位的特性。在輸入 CDMA 的波群以及元件輸出功率大於 28 dBm 的條件下，與 1.9 GHz 相差 1.25 MHz 處，其相鄰頻道功率反射 (Adjacent channel power rejection; ACPR) 為 -29.30 dBc；而與1.9 GHz 相差 2.25 MHz 處，其相鄰頻道功率反射為 -42.60 dBc。 實驗的結果顯示這種 HEMT 是相當適合應用在數位式與類比式的個人無線 通訊上 A planar-doped pseudomorphic high electron-mobility transistor (HEMT) was developed. Process procedures including mesa isolation, ohmic contact, gate recess, gate formation, passivation, airbridge and backside processing were described in this thesis. The DC characteristics of the HEMT were measured. The 1mm×15mm device exhibited a saturation current of 3.8A with gate-to-drain breakdown voltage over 14 V. The maximum transconductance of the device was over 260 mS/mm and the pinch- off voltage was -2.3 V. The knee voltage was 2.3 V and effective knee voltage was as low as 0.3 V. This paper also reports the microwave power performance of the device at 1.9 GHz and operated at a DC drain bias of 3.0 V and 4.7 V respectively. The power performance for the 1mm×15mm device demonstrated a maximum output power of 1.5W with a 40.8% power-added efficiency (PAE) under 3.0 V drain biased condition. Linear gain is 12.62 dB. The 1-dB compression power was 29.13 dBm with a power-added efficiency of 46.8%. The maximum output power the device developed was of 2.87W with a 52.3% PAE and 10.1 dB power gain under 4.7 V drain biased operation. The linear gain of the device is 13.65 dB. The 1-dB compression power was 33.2 dBm with PAE of 49.0%. The device also evaluated with CDMA modulation the output power spectrum with CDMA waveform shows output power higher than 28dBm at 1.9 GHz. The Adjacent Channel Power Rejection (ACPR) is -29.30 dBc at 1.25 MHz apart from 1.9 GHz. The ACPR is -42.60 dBc at 2.25 MHz apart from 1.9 GHz. These results indicate that developed HEMT is good for both analog and digital personal wireless communication applications.