The 2SK3515, 2SK-3515, K3515, 3515 is a 450V, 10A, 48W TO-220NIS Package MOSFET, The FUJI Electric manufacturer is a IC Chips with N CHANNEL SILICON POWER MOSFET for more details of 2SK3515 can be seen below.
The TIP140, TIP141 and TIP142 are 100V 10A 125W Silicon Epitaxial-Base NPN power transistors in monolithic Darlington configuration, mounted in TO-218 Package.
The 2SK1937-01, 2SK-1937, K1937, 1937 is a 500V 15A 125W N-Channel Power MOSFET, High Speed Switching - Low On-Resistance - No Secondary Breakdown - Low Driving Power - High Voltage - VGS = ± 30V